The Science of the Ask, Part 1: Why Legacy Giving Grows Your Annual Fund, Not Shrinks It

Legacy giving is often treated as the "I know it is important but not immediately important" fundraising stream: sitting to one side of the annual appeal, ignored whenever targets are under pressure. The unspoken fear is that asking about a gift in their Will might suppress a supporter's appetite to give today.

The evidence points the other way: supporters who arrange a gift in their Will tend to give more. That reframing matters, because what you’ll hear from a lot of legacy consultants is that it is a long-term investment that compounds.

The cannibalisation fear is the wrong way round

Ask why legacy giving stays on the back burner and you will hear the same worry: money is finite, so a future gift must mean less given now. It is intuitive, more so in a cost of living crisis, but here is why it should be dispelled.

The most rigorous look at this comes from Professor Russell James III at Texas Tech University, who tracked the same donors before and after they added a charity to their estate plan. Writing in the UC Davis Law Review, he found inflation-adjusted annual giving was, on average, about 77% greater after the charitable estate planning component was added than it was before (about $7,699 against $4,355 a year in the US study). The share of donors giving $1,000 or more annually rose in step, from 51.5% to 61.8%.

James is careful here: the data cannot prove the estate plan caused the increase, only that it followed, which is still what matters. No sign of the cannibalisation fundraisers may fear, and a substantially higher level of giving followed the decision.

Why the compounding happens

A gift in your Will is a statement about where someone stands: your cause now belongs in the story of their life, not just this month's direct debit. One likely explanation: the annual ask is no longer an interruption, just a small extension of a commitment already made. The hard part is done.

This is why we would argue legacy giving should be seen as the front door, not the fire exit. It is often the moment a supporter moves from transaction to belonging, and giving tends to rise across the board.

The UK evidence answers a different question, and adds a lever

James's study is American and, to our knowledge, not yet repeated in the UK. The UK evidence that follows does not replicate it: it answers a different, useful question, not whether legacy giving cannibalises annual giving, but whether the ask itself works.

In our experience, UK legacy pledgers are among the most committed supporters an organisation has. In a randomised controlled trial run by the Behavioural Insights Team with the Cabinet Office, Co-operative Legal Services and Remember a Charity, a plain prompt at the right moment, while people were actually writing their Will, roughly doubled the number who left a gift to charity, and adding a social cue took that further, to roughly trebling it.

Put the two together and the case, in our view, is for building the infrastructure legacy giving needs and investing in a well-timed, well-worded ask, since that is what actually moves pledges.

What this means for your fundraising strategy

If the evidence shows no sign of cannibalisation, and a substantially higher level of giving simply follows, legacy giving should not be first to go when budgets tighten. It should be one of the first things protected.

1. Stop framing it as a trade-off. A supporter who plans a future gift is not lost to the annual fund.
2. Treat the first gift as the start, not the finish. The value is what happens to that supporter's giving in the years between, not only the eventual gift. What we always bring back into the picture: stewardship (more on that later).
3. Make the ask early, and often. Start the conversation early, and run it at least twice a year. The UK trial adds one more reason to make sure you're also catching people at the moment they're writing their Will.

A simple next step

1. Check how many of your most donors have ever been asked about a gift in their Will.
2. Add one warm legacy prompt to a moment supporters already reach, with a social cue: many people like to leave a gift in their Will to causes they care about.
3. Track those supporters' annual giving over the following year, not just their pledge. James's own data runs over multiple years, so treat one year as an early read.

The great thing about legacy giving is that it does not ask you to choose between income today and tomorrow. Done well, it can grow both.

Where adeus fits

If most organisations know they should ask, the question left is how, and who. The instinct is to focus on your oldest community members, but the generation most legacy programmes overlook is often the one creating their first Will and prime for asking. adeus removes that hard part: our online Wills & legacy planning platform cuts the friction, so the first step costs supporters nothing and is quick and simple to start.

If you would like to see how that could work for your supporters, we would be glad to show you.

Contributed by Jonathan Ng

As Head of Partnerships at adeus, Jonathan works with schools and other institutions to build and grow legacy giving programmes through a modern, digital-first approach. He leads partner relationships from early conversations through to campaign launch, helping organisations shape the right strategy, messaging, and supporter journey. Outside of work, he is a dad, which gives him a personal appreciation for legacy, family, and planning for the future.

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Online will writing and gifts in wills

adeus runs a legacy giving programme for schools, charities and foundations. The organisation pays for supporters' online will writing, and supporters decide freely whether to leave a gift. Those gifts become legacy income, directed towards bursaries, capital projects and the organisation's mission. To see how it could work for you, email jonathan@adeus.life

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