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This is a summary of the GPI Working Paper “When should an effective altruist donate?” by William MacAskill (published in 2019). The summary was written by Riley Harris.

Effective altruists seek to do as much good as possible given limited resources. Often by donating to important causes like global health and poverty, farmed animal welfare, and reducing existential risks. Can we help more by donating now or later? This is the thorny question William MacAskill tackles in the paper “When should an effective altruist donate?”. He explores several considerations and presents a simple framework to help individual donors and philanthropic organisations decide for themselves. In MacAskill’s view, the most important considerations are:

  • Do we have particularly good opportunities to invest in movement-growth?
  • How quickly are the best opportunities being funded?
  • How will our ability to identify philanthropic opportunities change over time?; and
  • To what extent will our values improve over time?

The intuition behind waiting to donate

Some may be surprised that, rather than donating as soon as possible, it can be more effective to invest today and thereby donate more tomorrow. To strengthen our intuition for this idea, consider a slightly different context: an altruistic 18-year-old deciding how to maximise the impact they’ll have on the world. Rather than trying to have an impact immediately, it could be better for them to attend university first. In other words, we might encourage them to invest in their skills and networks at present, so that they can have a larger impact further down the line. Likewise, if returns on investment are sufficiently high, a donor might be able to help a greater number of future people by investing now to donate later.

Important considerations about when to donate

MacAskill identifies six important considerations about when to donate. He then also gives a qualitative framework for weighing these six considerations (p. 14-15).

1. Special relationships

Our special relationship to the present generation might encourage us to assign greater weight to their wellbeing and interests. We have special relationships with our family, friends and conationals. Perhaps we also have special relationships with all people alive today, compared to people in the future. Though moral philosophers typically argue that the interests of future people are in some fundamental sense just as important as our own, MacAskill thinks––given our moral uncertainty––we should still give slightly more weight to the interests of people we have special relationships to. 

2. Changing opportunities

All else equal, we should give when we have the best opportunities. Whether our opportunities are getting better or worse depends largely on two opposing effects. Firstly, the world is getting richer. Over time, this means that the most effective interventions will have already received sufficient funding, and the quality of our remaining opportunities will be worse. Secondly, we are also discovering new interventions (e.g., one of the best current ways to combat malaria is through distributing bed-nets, but in the future we might be able to cheaply eradicate malaria using gene drives). It’s difficult to know which of these effects is stronger, but MacAskill tentatively leans towards thinking our opportunities are getting worse over time. 

3. Getting better knowledge

Even if our opportunities are getting worse over time, we may be getting better at recognising which are our best opportunities. In general, our ability to identify important opportunities has been getting better over time. For instance, we have increasingly run randomised controlled trials which indicate which charitable interventions are the most helpful, and this information is increasingly aggregated and analysed by organisations like Givewell, leading to better information about which charities are likely to be the most cost-effective. This consideration tends towards giving later.

4. Value changes

If you decide to give later, your values may change in the meantime––indeed, many people have different values in their sixties when compared to their twenties. These changes might be viewed in a positive way––perhaps they will be the result of deliberation and improved understanding. They might, however, also be driven by less positive factors––for instance, if you became wealthier and at the same time came to believe that wealthy people shouldn’t donate much at all, then this change could be seen as suspiciously self-serving. Overall, MacAskill thinks that “...we should defer to our future selves on our values, if it’s the case that we think that their values are the result of ‘good’ processes, such as careful reflection, discussion with peers, consideration of moral argument, and so on” (p. 12). However, he also argues that not all value changes are good. 

5. Movement growth

The effect of donations on movement growth––for example by donating to an organisation that uses it to fundraise––can be viewed as a kind of investment that might have exceptional and compounding returns. For example, Giving What We Can estimates that each dollar donated to them eventually results in $100 in donations towards their top charities.[1]

6. Amount of money to donate

This consideration is deceptively simple in theory: all else equal, you should donate whenever you are able to give the most money. In the paper, MacAskill goes into detail on this category, considering taxes, uncertainty and financial investments. Perhaps surprisingly, weakness of will is relevant here. If you are likely to fail to meet your commitment to giving in the future, due to weakness of will, and you can’t mitigate this by setting up a donor advised fund, then perhaps you should donate earlier, even if it’s less effective, rather than risk failing to donate later.


  1. ^

    This is a best guess estimate, their lower bound estimate is $6.

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I think it's really worth highlighting that this Working Paper is from September 2019, I would add it to the title.

  • This was pre-chatGPT and the current AI explosion, which greatly impacts the value of donating now vs donating later for people who think there's a significant chance of risks from AI
  • This was pre-FTX, which made many people update on the value of investing in movement growth and on the possibility of sudden changes in funding
  • "Giving What We Can estimates that each dollar donated to them eventually results in $100 in donations towards their top charities" references an impact evaluation from 2015. The current link estimates $30. (Unrelatedly, but importantly, neither estimate is about the value of marginal extra donations)

Thanks for writing such a thoughtful comment. The post has to reflect the content of the paper, so I'm glad your comment can provide extra context. The post now reflects that the paper was written in 2019, and I plan to address the 30x figure soon.

Super accessible write up for a paper I find interesting but would never have read. Thanks for posting!

I really appreciate the feedback!

Thanks for the summary!

It is worth noting that, even if one thinks spending money later would be more effective, one could still donate to the Patient Philanthropy Fund!

Giving What We Can estimates that each dollar donated to them eventually results in $100 in donations towards their top charities.

The estimate for the counterfactual donations would be 30 $:

We estimate our giving multiplier for 2020–2022 is 30x [not 100x], and that we counterfactually generated $62 million of value for highly effective charities.

In this framework, I propose that Xnder ³amoXnt of mone\ to donate ́ Ze bXndle
considerations relating to taxes, weakness of will and uncertainty as well as financial

One thing I think is missing from the "how much you should donate" section above is a discussion about what kind of job the person is doing. Should the percentage be the same for someone doing Earning to Give vs someone working on a direct cause area?

IMHO this is a very personal, case-by-case calculation. 

A person will donate what they can rather than just a fixed percentage. But this can depend on many factors, not just jobs / income, but also expenditures (do they have kids? are they paying off college loans? a mortgage? ...) and potential risks (what if they lose their job? what if one of the kids gets sick? ...). 

That said, I believe there is a huge opportunity to maximise the "what they can donate" with a more structured approach. Today we have a very simplistic all-or-nothing donation model. For every dollar or euro you have, you either donate it (and lose it forever) or you don't donate it at all. I believe there could also be a happy-medium, I've started a draft post on that ... 

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