> Probably writing it all off against their tax bills.
I think you misunderstand how giving to charity works. This page gives some good examples:
---------------------------------------
https://financial-coaching.co.uk/blog/post/self-assessment-and-tax-relief-on-charitable-donations
Sue is a 40% taxpayer and donates £1,000 to charity.
The charity claims back basic rate tax of 20% from HMRC. That’s 25p for every £1 donated so the charity claims £250, making Sue’s gross donation £1,250.
Sue can claim the difference between her 40% rate of tax and the basic rate of tax of 20% claimed by the charity on her gross donation.
That’s a 20% difference. So, Sue claims 20% of £1,250 – a total of £250 – from HMRC.
If Sue was an additional rate taxpayer – paying 45% on her income – she would be able to claim the difference between her 45% rate of tax and the basic rate of tax at 20% claimed by the charity on her gross donation.
That would be a 25% difference. So Sue would claim 25% of £1,250 – a total of £312.50 – from HMRC.
---------------------------------------
A 45% taxpayer paid £1,250,000 gross would receive £687,500 net. They want to give their £1,250,000 gross income to charity. To do this, they give £1,000,000 to charity and the charity uses Gift Aid to claim a further £250,000, meaning that the charity has now received all of the £1,250,000. At this point, the donor is £312,500 out of pocket so they claim this back from HMRC. Net result:
Donor: £0
HMRC: £0
Charity: £1,250,000