Abstract
Nonprofits deliver services that benefit society in diverse ways, including developing medical treatments, providing education, supporting vulnerable community members, and protecting the environment. Donations are the lifeblood of many nonprofits, ensuring they can continue their essential work. Although donations from individuals in the United States totaled $374 billion in 2023, that represented a 2.4% year-on-year decline (adjusted for inflation; Giving, 2024). With Japan and the United Kingdom already in formal recession and other countries watching their economies anxiously (Buchwald, 2024), financial hardship is a growing reality for many around the world and this could see other countries experience similar declines in giving to those observed in the United States. It is therefore arguably more essential than ever for nonprofits to use evidence-based approaches in their fundraising campaigns.
One widely used fundraising tactic that has received significant scholarly attention is the use of incentives. An incentive is simply something that encourages someone to do something (Cambridge University Press, 2024). In this article, we focus on incentives for charitable giving, which we define as offers specifically designed to encourage someone to donate money. These incentives are typically offered by nonprofits, and sometimes also by the government.
Financial incentives are commonly studied, and the financial costs and benefits of giving have been proposed to be one of the key mechanisms that drive charitable donations (Bekkers & Wiepking, 2011). Furthermore, a range of incentives are commonly leveraged within fundraising campaigns: from match offers to direct mail premium gifts to tax benefits (e.g., Mally, 2023; Reis, 2018). Some of these incentives are more effective than others. Incentives like tax offers (e.g., Almunia et al., 2020), reputational rewards (e.g., Dannenberg et al., 2021), and matches (e.g., Goswami & Urminsky, 2020) are generally effective, whereas incentives like thank you gifts have been found to be less effective (e.g., Newman & Shen, 2012). We propose that diverging effects may be due to different incentives likely having different psychological underpinnings. For example, tax benefits may work because of the donor’s desire to reduce the cost of giving or minimize taxable income, match offers may work because the donor seeks to maximize the impact of their donation for others, and donor recognition may work because the donor seeks esteem from others and a positive reputation. Because of these diverse underlying mechanisms, different incentives have different effects overall and may be more effective for different kinds of people or charities.
The purpose of this article is to synthesize the existing evidence relating to the effectiveness of incentives for charitable giving. To do so, we systematically review over 40 years of research on incentives. To conceptualize the key considerations in understanding incentives, we propose a novel framework to integrate these disparate streams of research. By theorizing incentives as being either material or social in nature and as benefiting either the self or some other, we bring a new overarching perspective to this broad literature, provide summations of existing evidence, and identify significant future research opportunities. To our knowledge, our conceptualization of incentives as being self- versus other-benefiting is novel. Our intention is to synthesize and integrate diverse evidence into this overarching framework to provide the foundation for richer theorizing about the role of incentives in promoting generosity. To this end, we outline a research agenda of four broad theoretical propositions that warrant future exploration as scholarship on incentives develops: (a) other-benefiting incentives will be more effective than self-benefiting incentives, (b) giving can be promoted through offering social incentives that benefit others, (c) the effects of incentives will vary across people, cultures, and charity types, and (d) self-benefiting incentives may crowd out intrinsic motivations to give. We then close with practical, evidence-based guidance for fundraisers about which kinds of incentives are most likely to be effective in nonprofit campaigns, and which may unfortunately backfire.
Method
To identify the relevant research on incentives and charitable giving, we conducted a systematic review informed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocols (Moher et al., 2015). Systematic review methods introduce transparency and replicability to the traditional literature review, helping to minimize subjectivity by including all articles that meet certain, predefined requirements. Gazley (2022) proposes that systematic reviews are particularly valuable for relatively young and interdisciplinary fields like nonprofit studies, as they help distill the evidence base and speed up theory development by bringing knowledge that has been published in disparate disciplines together in one place. In the case of incentives, a systematic review allows us to consider research conducted by scholars in distinct disciplines and countries, using diverse methods, and to collate the evidence for and against a broad range of different incentive tactics.
Search Strategy
Initial searches were conducted in November 2019 across four databases. We first elected the two largest multidisciplinary academic databases (
To update and improve our searches, we supplemented these initial database searches with calls for unpublished data and snowball search methods. Open calls for unpublished data were distributed through Twitter (now called X) and the
Screening
We screened all identified articles in three rounds: first on title, second on abstract, third on the full text. To be included, the article needed to include at least one quantitative empirical study examining incentives for charitable giving. Qualitative articles, review articles, articles written in languages other than English, those published before 1980, and articles that were either not grounded in data (e.g., conceptual) or were not full length (e.g., conference abstracts) were excluded. The PRISMA flowchart (see Figure 1) summarizes the screening process, which resulted in a final corpus of 129 articles to analyze.
Flow Diagram of the Literature Search and Exclusion Process.
Data Extraction
To quantitatively summarize the corpus, the second author extracted data on a range of attributes of the articles. We identified the type of incentive being studied and the key findings reported in the article. To understand trends, we extracted information about the year of publication, disciplinary focus of the journal the article was published in, and country the data were collected in. To understand methods, we extracted information on the sample size, type of participants, design of the study, operationalization of giving, and type of nonprofit being considered. The coding spreadsheet summarizing this data is available on the Open Science Framework (OSF): https://osf.io/yw7r9/.
Results
Searches identified 129 relevant articles, which reported 153 unique studies. The unusual diversity in research designs, effect size estimates, and constructs in our corpus ruled out meta-analysis. Instead, we followed the Systematic Quantitative Literature Review method first outlined by Pickering and Byrne (2014), which involves capturing features of a corpus to generate a structured quantitative summary of a field and identify important gaps. This method has previously been applied to topics in philanthropy (e.g., Chapman et al., 2021b) and allows us to summarize the corpus quantitatively at a high level to give a bird’s-eye view of how incentives for giving have been studied. In that section, we generally report frequencies at the study level. However, data on journal discipline and year of publication is aggregated at the article level. After the quantitative summary, we progress to a more thorough qualitative synthesis of corpus.
Quantitative Summary
There has been a slow but steady increase in the number of articles exploring the effects of incentives on charitable giving (see Figure 2). Our corpus consists of 85% published articles and 15% unpublished studies, reported in either working papers, conference papers, or theses. Experimental (54%) and archival (40%) methods were the most common approaches to studying the effects of incentives. Samples were generally drawn from the community (78%) rather than student populations (16%), but were rarely nationally representative (just 3% of studies). Because of the popularity of archival methods (e.g., tax file data), sample sizes were typically large: ranging from 43 to 59,131,435 with a median sample size of 3,588. Median sample size was much larger for archival studies (
Number of New Articles Published Each Year That Considered Incentives for Charitable Giving (
Looking at the disciplinary focus of the journals in which articles have been published, this topic is dominated by economists (65% of published articles; see Figure 3). Only a handful of articles on incentives for giving have been published in marketing or specialty nonprofit studies journals. Furthermore, none were published in psychology journals. Given the relevance of incentives to marketing campaigns, psychological underpinnings of behavior, and outcomes for the nonprofit sector, these lacunas may represent opportunities to ignite research and discussion of incentives in these disciplines. Incentives for charitable giving are primarily studied in the United States (71% of studies; see Figure 4).
Breakdown Showing the Disciplinary Focus of the Journals Where Research on Incentives Has Been Published (
Countries in Which Research on Incentives for Charitable Giving Has Been Conducted (
Qualitative Synthesis
To conceptualize approaches to understanding incentives for charitable giving, we propose a new framework to overlay and organize the literature. Our framework (summarized in Figure 5) integrates two broad orientations that we observed in research on charitable incentives: type of incentive (material vs. social) and beneficiary of the incentive (self vs. other). With 129 articles included in our review, we are unable to discuss each paper in depth and instead use illustrative examples to summarize the overall state of the literature. A table summarizing all included articles by category is, however, available in the supplementary materials on the OSF.
Conceptual Map of Literature on Incentives for Giving, Integrating Type of Incentive (Material vs. Social) With Beneficiary of Incentive (Self vs. Other).
Incentives may be material or social in nature.
Research on donor motivation has identified two broad orientations that can influence giving behavior: self-orientation and other-orientation. These orientations are studied explicitly (e.g., Chapman et al., 2020; Konrath & Handy, 2018; Thottam et al., 2024) and also implied in more general summaries of donor motivation (Bekkers & Wiepking, 2011). For example, Bekkers and Wiepking’s (2011) landmark review summarizes the donor motivation literature into eight mechanisms, some of which are more self-oriented (e.g., costs and benefits, reputation) and some of which are more other-oriented (e.g., altruism, efficacy). Konrath and Handy (2018) also classify their fiscal incentives and social punishment motives as being self-oriented. Rather than assuming that incentives are
Self-Benefiting Incentives
When the benefits offered by the incentive would accrue to the donor’s own self, we label these
Material Self-Benefiting Incentives
Tax Benefits
Tax benefits are the dominant form of incentive studied in the literature (
Generally, giving is seen to be price elastic, meaning that tax incentives motivate giving: the greater the tax benefit, the more people give (Almunia et al., 2020; Brooks, 2002; Holmes, 2009). People will even shift their donations forward in anticipation of an expected reduction in tax-based incentives (Bakija & Heim, 2011; Barrett et al., 1997). Estate tax rates also affect rates of and value of bequests (gifts left in Wills; Brunetti, 2005; Dexter, 2014; Joulfaian, 2000), suggesting the tax benefits partially incentivize such gifts.
Although most of the incentives studied consider their impact on giving at the micro (i.e., individual) or meso (i.e., organizational) levels, some of the research on tax incentives has considered impacts at the macro (i.e., sectoral or societal) level; specifically asking if such incentives are fiscally efficient. In other words, do the total charitable donations generated by tax incentives make up for the losses in tax revenue? Some studies have found tax deductions to be fiscally efficient (Hossain & Lamb, 2012b), others suggest they are inefficient (Duquette et al., 2018; Fack & Landais, 2010; Grant & Langpap, 2022; Lin & Lo, 2012), while some find they essentially only break even (Yetman & Yetman, 2013).
Tax incentives work better for some kinds of charities than others (Yetman & Yetman, 2013). For example, Brooks (2007) found that in the United States giving to multi-mission charities reacted more strongly to tax incentives than giving to, for example, health charities. Also in the United States, Duquette (2016) found giving to health and home care charities was more responsive to tax incentives than giving to education and arts charities. In Canada, tax incentives affect giving to secular causes, but not religious ones (Chan & Lee, 2016; Hossain & Lamb, 2012b). Also in Canada, a 10% decrease in the price of donation (i.e., improvement in tax incentive) increases the probability of making a social services donation by about 4% and increases the probability for an international donation by only 2% (Hossain & Lamb, 2012a).
Beyond North America, the effect of tax incentives varies across national contexts. Tax benefits have been found to promote donations in Singapore (Chua & Wong, 1999; Ming Wong et al., 1998), Spain (García & Marcuello, 2001), and Germany (Paqué, 1986), but not to affect giving rates in Taiwan (Chang, 2005). In France, tax incentives work better for the most generous donors (Fack & Landais, 2010), whereas in the United Kingdom, tax incentives affect whether people give, but not how much they give (Jones & Posnett, 1991a, 1991b).
Different types of people also seem to be more or less affected by tax incentives. People who are more tax-motivated are, unsurprisingly, more affected by tax incentives (Tiehen, 2001). Tax incentives are generally found to work best (or perhaps even exclusively) among people with higher incomes (Auten et al., 1992; Fack & Landais, 2010; O’Neil et al., 1996), though some have found the opposite (Grant, 2016; Lin & Lo, 2012). Men may be more sensitive to tax benefits than women are: Yörük (2010) found that wife-deciding couple households were less sensitive to tax incentives than husband-deciding or joint decision couple households.
Thank You Gifts
Sometimes charities offer a gift to potential donors to thank them for their support. A thank you gift could be offered before a donation is made, which is called an
Although the use of thank you gifts is relatively widespread in nonprofit fundraising (e.g., Reis, 2018), there is very little evidence that they are effective in generating donations. One study did find that thank you gifts can work, but only when the gift offered was high quality (e.g., leather vs. plastic luggage tag) and unconditional (Eckel et al., 2016). Another study found a small benefit of thank you gifts from charities that were rated unfavorably but that the same gifts had either no effect or even negative effects when offered by a charity that the participant already liked (Chao & Fisher, 2022).
Gifts often have no effect. For example, actual money (i.e., a coin) attached to the donation letter did not affect donation responses to a charity appeal in Korea (Kim, 2015). Likewise, conditional gifts did not impact the likelihood or value of donations in a University alumni giving campaign (Eckel et al., 2016). A field experiment in the United States considered the impact of either a cash gift ($0.25 coin) or a non-cash gift (greeting card) compared with a control condition (no gift). Although the response rate significantly improved in the cash gift compared with the other two conditions, half of all responses were people simply returning the cash. Accounting for this, the monetary gift resulted in lower donation rates than in the other conditions, whereas the non-monetary gift had no effect compared with control (Yin et al., 2020). Given the cost of offering gifts, even a neutral outcome is worrying.
Unfortunately, thank you gifts often backfire and generate negative consequences. Across five studies, Newman and Shen (2012) consistently show that average donations are lower when a gift is offered than when no gift is offered, and that negative outcome was not attenuated by the desirability or value of the gift. Similarly, including the gift of a free map alongside an information leaflet for visitors to a Costa Rican national park not only did not increase voluntary contribution rates or average gift relative to a control condition, when paired with social information about the contributions of previous visitors the gift actually diminished donations (Alpízar & Martinsson, 2012). In another study, the promise of a travel coffee mug for donating at a certain rate backfired: half as many people donated compared with the control condition (Chao, 2017). This depression effect may be most likely among the most generous donors (Mills et al., 2014).
Some studies have asked people to predict how others feel about thank you gifts. Some people assume thank you gifts will promote giving (Newman & Shen, 2012). Using a role-playing methodology, where participants were asked to reflect on how a hypothetical other person would feel about receiving premium gifts as incentives for their donations, Bennett (2007) found that people were supportive of small incentives for smaller donations (i.e., receiving a computer game worth £10 if donating £75), but not as supportive of larger incentives for larger donations (i.e., receiving an airline flight worth £200 for donating £1,000). In that study, people who were more committed donors were generally less supportive of the use of such premium incentives. Thus, people seem to feel that only small thank you gifts are acceptable from charities. People also seem to be attuned to the likelihood that thank you gifts can backfire. In a series of studies, Newman and Shen (2012) found that participants consistently predicted that offering a conditional thank you gift (desirable or otherwise) depressed the average or median donation value relative to a control condition.
Rebates
Another common area of scholarship on material incentives is whether the offer of rebates can promote giving. With rebates, potential donors are offered the promise of receiving a portion of their donation back after giving. This is a tactic that, to our knowledge, is not widely practiced by nonprofit fundraisers but is nevertheless widely studied using economic game type scenarios for its theoretical equivalence to tax incentive policies.
Typically rebates promote giving (e.g., Bekkers, 2015; Davis, 2006; Donazzan et al., 2016; Eckel & Grossman, 2008), though perhaps only lifting the conditional value of the donation but not likelihood of a donation at all (Eckel & Grossman, 2017). However, one study found that when continuing donors received a rebate offer they were significantly
Other Material Offers
A few studies have considered the effect of offering other material rewards. These are generally found to be effective. For example, German participants in two-round dictator games donated more in the first round when each €0.25 donation earned them tickets in a lottery for which they could win €100 (Gallier et al., 2017). Likewise, people are more likely to engage in an effortful voluntary task to earn a donation for charity when they are offered a financial incentive than when no incentive is offered (Meyer & Tripodi, 2017), though this effect may be strongest when their efforts are private (vs. public; Ariely et al., 2009). This suggests the importance of social incentives, which we now consider.
Social Self-Benefiting Incentives
Visibility
Whether or not a person’s donation value will be visible to others can affect how much they donate (Meyer & Tripodi, 2017). For example, Harbaugh (1998) examined archival data from alumni donations to a prestigious law school that used different donation visibility conditions over time and found that donations will be between one quarter and one third higher when exact donations are reported publicly than when donations are not reported publicly. People will also exert more effort to earn a donation for charity when their efforts are public than when they are private (Ariely et al., 2009). Finally, men are more affected by donation visibility than women, and will increase their performance in a donation-generating task more than women when their prosocial performance is compared with that of others (Böhm & Regner, 2013). This suggests that visibility incentives will work better for some people than others.
Recognition
The question of donation visibility relates also to the notion of recognition: perhaps the specifics of their donation will not be visible, but they may be recognized, publicly or privately, for having donated above a certain threshold. For example, the chance to win public recognition at a charity event (i.e., having their name printed on a sponsor banner and read aloud during the ceremony) increased donation likelihood relative to a no recognition or material reward offer without detracting from donors’ intrinsic motivation to give (Mills et al., 2014). A series of studies in France showed that the offer of private recognition (i.e., receiving a thank you email from the fundraising manager) did not affect donation responses but the offer of public recognition (i.e., a thank you message from the charity posted on their Facebook wall) did increase the likelihood that they would donate their €5 participation fee (Denis et al., 2020).
Not only the likelihood of any donation being made but also the average donation size can be affected by the offer of recognition. A field experiment at a University-based public service organization found that when offered the chance to have their names published in an upcoming newsletter for donations over $100, the likelihood of any donation being made increased by 2.7% and the average value of the gift increased by 14% (Karlan & McConnell, 2014).
Both positive and negative recognition can affect giving. Publicly recognizing the most generous donors may activate the desire to seek prestige from being a high-level donor, whereas publicly recognizing the least generous donors may activate a desire to avoid the shame of being a low-level donor (see Samek & Sheremeta, 2017). Thus, both forms of recognition have been shown to promote giving relative to a no recognition baseline.
Some people appear more incentivized by recognition than others. Kottasz (2004) found that lawyers are over three times more likely to want recognition for donations than were accountants or investment bankers. Public recognition is motivating for people who are high in the need for social approval, but recognition may actually reduce donations from those who are low in that need (Denis et al., 2020). Public recognition may also reduce donations for people who have an independent self-construal (Simpson et al., 2018).
Reputational Benefits
The effects of both visibility and recognition suggest some underlying reputational incentive. Indeed, reputational rewards have also been studied explicitly. Archival analyses of the annual giving of 22,641 alumni at one U.S. university found that donations increase in years that the college achieved greater athletic prestige, suggesting donors are seeking reputational rewards by affiliating with winners (Holmes, 2009). More directly, a field experiment conducted with 933 German movie-goers offered various forms of incentive to promote cash donations for a climate campaign. A “social status gift” of a mug or tote bag that included the campaign branding as well as the text “Supporter of the Climate Campaign” performed significantly better than other conditions, including donation visibility, recognition on social media, and the identical gift without the supporter message (Dannenberg et al., 2021).
Other Social Rewards
People may also be incentivized by other social rewards, such as being thanked or invited to social events. Having someone thank you for an action is a form of social approval. Experiments involving over half a million thank you calls over a period of 6 years, however, concluded that receiving a thank you call for a donation had no effect on subsequent giving to either public radio stations or a national nonprofit (Samek & Longfield, 2019). Nevertheless, young affluent men reported that social rewards in the form of invitations to special events like galas, black tie dinners, and private gallery viewings were very motivating in their giving decisions (Kottasz, 2004).
Summary of Self-Oriented Incentives
Mixed results were found for material self-oriented incentives. Generally, support was found for the positive impact of tax incentives, though data was mostly restricted to the U.S. context. Tax incentives work differently for different people and to different charities. The jury remains out as to whether they are fiscally efficient overall. Rebates were generally found to be effective. Thank you gifts often backfire and are not recommended.
Social self-oriented incentives are generally effective, though are more effective for some people than others. Visibility of donations, public recognition for giving, and reputational rewards generally promote giving—both the likelihood of a gift being made and the value of the gift. Just like material thank you gifts, however, thank you calls do not seem to incentivize people to give more.
Other-Benefiting Incentives
Until now we have focused on incentives that benefit the self. It is also possible to incentivize giving by offering benefits to some other. Two type of material other-benefiting incentives have been studied: matching offers and thank you gifts for others. We found no study that had considered social other-benefiting incentives.
Material Other-Benefiting Incentives
Matching Offers
Matches involve the promise that any donation made will be matched at a certain rate, whether by the organization itself, another donor, or a major grant. They can be expressed as either a ratio or a percentage. For example, a 1:1 (or 100%) match means every dollar donated by the donor will be matched by another dollar, making the resulting contribution $2 for a cost of just $1 to the donor. A 0.5:1 (or 50%) match, in turn, means that every dollar that is donated will be matched by another $0.50 from another source, making the total contribution $1.50 for a cost of just $1. Unlike rebate offers, matching offers are widely incorporated into real nonprofit fundraising campaigns (e.g., GoFundMe, 2024; Mally, 2023).
Matching offers have generally been shown to promote giving (Baker et al., 2009; Charness & Holder, 2019; Deck & Murphy, 2019; Goswami & Urminsky, 2020; Helms McCarty et al., 2018; Karlan & List, 2007). However, they may work better for existing donors than new ones (Helms McCarty et al., 2018). Matches rarely backfire (though see Eckel & Grossman, 2008, which the authors ascribe to challenges with field research design).
When it comes to matches, bigger is generally better. For example, one U.S. field experiment found that unconditional average gifts were higher for existing donors who receive a 100% match offer (1:1) but not for those who receive a 10% match offer (0.1:1) compared with those who received no match offer (Helms McCarty et al., 2018). Considering gradations on this continuum, evidence suggests that 50% matches promote giving, while 25% matches do not (Meier & Frey, 2004). Further evidence of the size bias: matches that take the form of a fixed value bonus added to the donation only encourage new donors to give when the bonus is substantial (i.e., $10) but not when it is smaller (i.e., $5 or $1; Helms-McCarty et al., 2016). There may, however, be a limit to the “bigger is better” heuristic when it comes to matches: very large match offers (i.e., 3:1) may not be significantly more effective than smaller ones (i.e., 1:1; Karlan et al., 2011; Karlan & List, 2007).
There remain a few caveats and considerations to the use of matching offers. Willingness to give may be diminished in the long run, as people incentivized with a match offer may choose to give less in subsequent, non-matched appeals (Meier, 2007). It is also possible that the effects of matches are not so much about the incentive itself but rather that the presence of a lead donor may signal quality to other donors (Huck et al., 2015; Huck & Rasul, 2011). Contingent matches—where the match is only made if a certain percentage of other donors also contribute—may also be effective. Anik and colleagues (2014) considered the effectiveness of 25%, 50%, 75%, and 100% contingent matches and found a 75% contingent match to be most effective at getting people to upgrade from single gifts to recurring donations: the match would only be made if 75% of other donors also upgraded. The authors propose that this level of contingent match is effective as it simultaneously provides a high degree of social proof, while maintaining a target that could reasonably be achieved.
The impact of matches is often contrasted with the impact of rebates (see previous section on rebates). When considering the overall cost of giving, a 20% rebate is equivalent to a 25% match: a dollar worth of value in each case would cost the donor $0.80. With the rebate, they donate $1 but receive $0.20 back (i.e., benefit to self); with the match, they donate $0.80 and have an additional $0.20 provided through the 25% match (i.e., benefit to other). Importantly, the match is sent to the recipient and not the donor. This is why, though they may be equivalent in terms of cost of giving, we argue that matches are other-benefiting, while rebates are self-benefiting.
Almost every study that has compared these incentives head-to-head has found that matches outperform rebates in encouraging donations (Bekkers, 2015; Davis, 2006; Davis et al., 2005; Eckel & Grossman, 2003, 2006a, 2006b, 2008, 2017; Gandullia, 2019; Gandullia & Lezzi, 2018; Hungerman & Ottoni-Wilhelm, 2021; Kamas & Preston, 2010; Lee et al., 2018; Lukas et al., 2010; Sasaki et al., 2021; Scharf & Smith, 2015). These studies have typically focused on what works best (i.e., effects) rather than why they work (i.e., mechanisms). We propose that this divergence in effects, despite match and rebates equivalence in terms of price of giving, may be because people have different psychological reactions to the two offers—with rebates activating self-oriented motives (i.e., getting a financial kickback) and matches activating other-oriented motives (i.e., making more of a difference on the cause). To our knowledge, this is novel conceptualizing and warrants explicit empirical examination.
The enhanced effectiveness of matches over rebates is especially pronounced among men (Lee et al., 2018) and people motivated by warm glow (Gandullia, 2019). A single study found rebates to be more effective than matches (Blumenthal et al., 2012), though with a caveat: although individual gifts were higher for rebates, the total raised was still higher with matches. No difference was found between rebates and matches in a sample of donors who pay by check (Lukas et al., 2010), though again more donations were generated overall in the match condition.
Gift for Others
We have seen that most of the evidence about the effectiveness of gifts to self suggests they may actually be detrimental. One study investigated whether thank you gifts would be effective if they were advertised as being of benefit to others (Newman & Shen, 2012). People said they were hypothetically willing to donate more when a thank you gift they received (e.g., tote bag) was framed as benefiting others (i.e., when other people see the charity logo it will raise awareness for the cause) than when framed as benefiting themselves (i.e., it can be used for purchasing groceries). However, hypothetical donations in the other-benefiting condition were still generally lower than in the no gift condition (Newman & Shen, 2012). Another study found the promise of an other-benefiting gift (i.e., 60 meals to families in need) backfired among the most generous donors, who were less likely to donate than in a control condition with no gift offer (Chao, 2017).
Social Other-Benefiting Incentives
We found no studies in the corpus that examined the effects of social other-benefiting incentives, or incentives that bestow social or reputational rewards on someone other than the donor. It may be that studies have examined contexts where this may occur, such as crowdfunding or legacy giving, without examining these as incentives explicitly. In the Discussion, we return to this point and discuss ideas for future research in this space.
Summary of Other-Oriented Incentives
Two material other-oriented incentives have been examined: matching offers and thank you gifts. The consensus is that matches are effective. In direct competition with rebates, matches typically win. Bigger matches are generally better, though perhaps with a point of diminishing returns. Thank you gifts that benefit others are more effective than thank you gifts to the donor themselves, though they are less effective (or at best equally effective) as offering no gift. Social other-oriented incentives have not yet been studied.
Discussion
We systematically reviewed the past 40+ years of quantitative research investigating the impact of incentives on charitable giving and synthesized learnings from 153 unique studies. Most of the incentives that have been studied to date do work to some extent. The glaring exception is the use of thank you gifts, which not only generally do not encourage donations but sometimes even backfire and reduce giving. Both material and social incentives can be employed to promote giving, though different incentives may work better for different people and charity contexts.
In this article, we present a novel way to delineate incentives: as either self-benefiting or other-benefiting. Most research has focused on incentives that benefit the self, less so on incentives that benefit some other. Yet, on balance, it may be that other-benefiting incentives are more effective than self-benefiting incentives. Head-to-head tests of rebates (self-benefiting) versus matches (other-benefiting) consistently find that matches are more effective than rebates, holding the cost of giving constant. Framing thank you gifts as being other-benefiting (vs. self-benefiting) may also attenuate some of the negative effects gifts can generate. This leads us to propose:
Future research could test this proposition directly using experiments that manipulate the target that benefits from the incentive (donor or other). Giving to certain types of charity (e.g., medical research, religion) is more commonly motivated by self-oriented concerns, while giving to other types of charity (e.g., social services, international) is more commonly motivated by other-oriented concerns (Chapman et al., 2020; Thottam et al., 2024). It may therefore be valuable to test the effectiveness of self- versus other-benefiting incentives in charity contexts that are more likely to be self versus other motivated. This could be achieved using factorial experimental designs or choice modeling approaches.
Both material and social incentives can be effective, though material rewards have been studied in far greater depth. More evidence needs to be generated around when and how social incentives work and for whom. Early evidence suggests that the effectiveness of social rewards may be especially dependent on characteristics of the donor. Most critical is the need to consider social other-oriented incentives, which have not yet been studied. We propose:
Future research could directly examine how social incentives that benefit some other can encourage donors to give. One common practice is memorial gifts, which involve donations being made in the name of someone who has passed (Penner & Kelley, 2021). Other forms of tribute or in honor giving that are becoming common practice include asking for donations in lieu of birthday, wedding, or graduation presents (e.g., Ibrisevic, 2023). Donations made in others’ names may involve formal recognition such as naming rights (for large gifts) or simply the knowledge that a certain amount has been raised in the loved one’s name. It is estimated that a third of donors worldwide have made memorial or tribute donations, and these products are offered by many nonprofits (DonorSnap, 2024). Yet, to our knowledge, these practices have not yet been examined empirically as a form of incentive. Archival studies may be useful to examine the impact of the introduction of such memorial offers on subsequent donations within charities. In addition, experiments can be used to test different offers and framings of other-benefiting social incentives.
Incentives appear to vary in effectiveness across individuals and causes. Social rewards like visibility and recognition, for example, are more effective for some people than others (e.g., Böhm & Regner, 2013; Denis et al., 2020). Tax incentives have also been shown to be more effective for some types of charitable cause than others (Hossain & Lamb, 2012a).
Prosocial behavior, including charitable giving, has been theorized and shown to vary significantly across cultures (e.g., Luria et al., 2015; Wiepking, 2021). It therefore presents a significant problem of generalizability that 71% of the existing research on incentives is focused on just one national context (i.e., the United States). For example, the summarized evidence suggests tax incentives work in the United States (e.g., Brooks, 2007; Duquette, 2016). However, data from other countries suggests they are not universally effective (e.g., Chang, 2005; Fack & Landais, 2010). For these reasons, we propose:
Further research is needed to understand whether the effects of incentives are relatively universal or contextually bound. As with other topics in philanthropy that have found cross-national differences (e.g., Chapman et al., 2021a; Einolf, 2017; Luria et al., 2015), comparative research is needed to understand how incentives for charitable giving operate in different cultures and for different kinds of charities. Basic cross-sectional research could also examine whether different types of people (e.g., men vs. women, religious vs. secular, egoistic vs. altruistic) are motivated equally or differently by incentives. A broad range of moderators could be examined—whether experimentally or cross-sectionally—including gender, age, religiosity, cultural factors, and individual differences such as extraversion, empathy, social dominance orientation, or values.
Some of the incentives studied—most notably thank you gifts—had unintended negative effects. This shows that incentives sometimes backfire immediately. However, psychological theories of human motivation (e.g., Self-Determination Theory; Ryan & Deci, 2000) suggest that incentives could sometimes work in the short term but may still backfire in the longer-term. While rarely touched on in the corpus (though see Meier, 2007), the risk that incentives may accidentally crowd out intrinsic motivation and therefore be detrimental to longer-term giving is a real one. Extrinsic motivations, such as pressure or rewards, have been theorized and demonstrated to crowd out intrinsic motivation in prosocial contexts (Chapman et al., 2024; Deci et al., 1999; Wollbrant et al., 2022). This is because when people think back about their choice to donate and can explain it to themselves in terms of some external factor (e.g., reward or threat), they are less likely to internalize the notion that they had freely chosen to give and therefore to ascribe the behavior as being something they value and should repeat (Cialdini, 2001). Behaviors that are freely chosen are more likely to be sustained than behaviors that are externally regulated (Teixeira et al., 2012). On this basis we propose:
Future research could explore the idea of crowding out in longitudinal archival studies that follow donors who did and did not receive donation incentives over a longer period. Psychological mechanisms such as motivations can also be studied using experimental designs that test mediation models to understand the effects of incentives on intrinsic versus extrinsic motivations for giving and the flow-on effect to future giving intentions. Crowding out risks may be greater with material than social incentives, and that idea also could be tested experimentally.
Strengths and Limitations
The current systematic review employs transparent and reproducible methods to capture a broad sample of quantitative research on incentives, published over more than 40 years and across diverse disciplines. We made a conscious effort to include unpublished studies (representing 15% of the corpus) to overcome the danger of publication bias that, because studies with positive effects are easier to publish, could lead to an overly optimistic picture of the effectiveness of incentives.
Our searches could have been improved by the inclusion of a keyword relating to fundraising. Nevertheless, we conducted forward and backward citation searches on every article in the corpus, meaning that any article that was not in the original searches but that was cited by or had cited one of the identified articles was also included. Thus, snowball sampling allowed us to fill any gaps in our original search protocols.
All systematic reviews are limited to the corpus of research available. Our study is no exception, so we have taken this opportunity to highlight important lacunas and opportunities for future research to address any gaps in the current evidence base. Ideally, our systematic review would have included a meta-analysis to quantify the relative effect sizes of different incentives. However, the diversity in research designs, effect size estimates, and constructs was much broader than is typical for other topics in the field. We were therefore not able to extract effect sizes that could be compared meaningfully with this corpus. Nevertheless, our synthesis has highlighted which incentives typically encourage donations and which typically do not. We also make the corpus freely available on the OSF for scholars who may wish to meta-analyze subsets of the data.
Managerial Implications
Having reviewed and summarized over 40 years of research on incentives for charitable giving, we can make some broad recommendations for practitioners about the tools that are typically effective (or not). First, giving can be incentivized by either material or social rewards, and by offers where the benefit accrues to either the donor themselves or some other. However, some incentives are more effective than others.
Tax incentives are typically shown to encourage donations. Although there is debate about whether tax incentives raise more money than they cost the government, from a nonprofit perspective they are useful tools to leverage gifts. Continued engagement with donors around tax time highlighting the benefits accruing from tax-deductible donations is a sound approach.
Matching offers—where donors gifts are matched by additional support from a lead donor or grant—also appear to be consistently effective in lifting donations. In general, larger matches work better than smaller matches, but the point of diminishing returns may be reached somewhere between a 1:1 and 3:1 match. Match offers have consistently been shown to be more effective than rebate offers. We therefore recommend using match incentives over rebate offers, with a 1:1 match possibly returning best value for money.
Gifts, whether unconditional premiums or conditional thank you gifts, are generally not effective and sometimes even backfire. In other words, offering such gifts does not generate higher rates of giving and sometimes even results in lower levels of giving. Exceptions may be when high-value unconditional gifts are offered or when the gift is framed as being of benefit to someone other than the donor. However, even in such cases the gift offers typically do not raise more money than offering no gift. Because gifts are often costly, the evidence that they do not increase giving and sometimes even reduce it leads us to recommend that fundraisers should not use gift incentives in fundraising appeals.
Social rewards—such as the effect of donation visibility, recognition for certain donation levels, and invitations to prestige events—may be more motivating for men and people who have a higher need for social approval. More research is needed about how different kinds of people respond to incentives in general. In the meantime, fundraisers are encouraged to A/B test their offers and consider how different donor segments respond to different incentives.
Conclusion
This article reviews evidence about the impacts of incentives on charitable giving from 153 studies published over the last 40 years. To make sense of such a large corpus of knowledge, we overlay a novel framework proposing that incentives can be conceptualized as either material or social in nature and as either self- or other-benefiting. Overall, we find that most of the incentives that have been studied to date are effective to some extent (e.g., tax rewards, rebates, match offers, recognition). Thank you gifts, however, generally do not encourage donations and sometimes even backfire. Both material and social incentives can be employed to promote giving, though different incentives may work better for different people and charity contexts. Match incentives are typically more effective than rebate incentives, which we propose may be driven by different psychological underpinnings associated with incentives that benefit some other (e.g., matches) or benefit the self (e.g., rebates).
Based on our synthesis of the literature and novel theorizing, we propose a research agenda with four theoretical propositions that warrant further investigation: (a) other-benefiting incentives may be more effective than self-benefiting incentives; (b) social incentives that benefit others can promote giving; (c) incentives may work differently across people, cultures, and charity types; and (d) self-benefiting incentives may crowd out intrinsic motivations to give. These propositions can serve as a jumping off point for future scholarship on incentives for charitable giving.
Footnotes
Data Availability
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Cassandra Chapman is the recipient of an Australian Research Council Discovery Early Career Researcher Award (project number DE220100903) funded by the Australian Government. The authors also wish to thank Jessica Spence and Lucas Dixon for their contributions to initial data screening.
