Your donations will qualify for Gift Aid as long as they’re not more than 4 times what you have paid in tax in that tax year (6 April to 5 April).
The tax could have been paid on your income or capital gains.
If you have claimed more tax relief than you are entitled to, you will need to notify the charity and pay back any excess tax relief to HMRC.
You must tell the charities you support if you stop paying enough tax.