Disclaimer: When I’m not co-editing Better Nation I’m a professional charity fundraiser, and my work includes major donor giving. I write here, as ever, in a personal capacity.

David Cameron has promised to consider charities’ calls to dismiss plans in the Budget to cap tax relief on charitable donations.

At the moment, whenever basic rate taxpayers donate to charity, whatever they would have paid in tax goes to the charity as well – all thanks to the little Gift Aid box you usually tick on a donation form. For higher rate taxpayers, some of the tax due goes to charity (the amount of tax due under basic rate) and the rest (on the higher rate) can be reclaimed by the individual. The Treasury wants to cap the amount which can be reclaimed to £50,000 per annum.

Of the £11 billion given to UK charities last year, almost half came from only 7% of donors. Attempting to end tax loopholes should be commended, but it is foolish to penalise the people who help ensure this country has the arts, education, museums and, I dunno, the Big Society it merits.

The Conservatives themselves are trying to boost private giving to the arts. Osborne’s Budget in 2011 added a new tax break for charitable giving, allowing anyone leaving 10% of their estate to charity to reduce their inheritance tax bill from 40% to 36%. In this situation, charities rightly feel wronged by Osborne’s decision.

It is the major arts and education institutions that largely benefit from major donor giving. In Scotland, the principals of five universities and the directors of National Museums Scotland and the National Galleries of Scotland have called on the UK government to scrap its tax relief cap. It is unlikely the revitalisation last year of the National Museum of Scotland or of the Scottish National Portrait Gallery could have been completed without measures like this to encourage major donor giving.

Other charities are of course affected too, and the SCVO is supporting the ‘Give it back, George’ campaign, while major Scottish philanthropists like Sir Tom Hunter and Sir Ian Wood have warned the move will have a ‘disastrous’ effect on charitable giving.

I have worked in encouraging major charitable donations. Part of my previous job was trying to figure out why wealthy people would be motivated to support the capital project I worked on, and I wrote and rewrote many guides to demonstrate this tax relief opportunity which Osborne wants to end.

I don’t think any of these guides were ever used in meetings with potential donors.

Russ Alan Prince and Karen Maru File wrote a book in 2001 called The Seven Faces of Philanthropy. Like most fundraising, it’s good common sense. People have different reasons and motivations for giving, and they can be summarised in seven different types:

1. The Communitarian: Doing Good Makes Sense
2. The Devout: Doing Good is God’s Will
3. The Investor: Doing Good is Good Business
4. The Socialite: Doing Good is Fun
5. The Altruist: Doing Good Feels Right
6. The Repayer: Doing Good in Return
7. The Dynast: Doing Good is a Family Tradition

I have met donors across all seven faces, and number three, the one who thinks about the tax advantages of philanthropy the most, shows up the second least often. (Number seven, The Dynast, is the least frequent, but I think that’s more to do with a difference between British and American philanthropy.)

Should philanthropy happen without financial inducements? Ideally. Of course. Will it happen as often? I doubt it. Several beneficiaries of major philanthropy, like UNESCO and the National Theatre, have already reported that large pledged donations are threatened by this move. Charities are squeezed right now: rising inflation, falling income, increasing demand for services. To make a change like this – even if most major donors don’t consider it before giving –  without prior consultation with charities literally wipes millions from predicted incomes going forward, affecting future plans and service provision.

I would like the Treasury to do more, a lot more, to end tax avoidance. Some people are probably funnelling funds to made-up charities to benefit from this relief. But for most major donors, who are giving a lot of money for their name to be etched in stone forever on a wall somewhere, for everyone to see, including HMRC, isn’t really what I consider the behaviour of a tax dodger.