HMRC Self Assessment Calculation - problem with Gift Aid

KC62

I'm in the process of completing my Self Assessment for 2019-20 and am experiencing a problem with Gift Aid relief.
I'm a higher rate taxpayer and claim tax relief for a modest sum that I give to charity each year. The Self Assessment calculator has accepted the sum claimed and gives me an additional sum on the basic rate band to give the higher rate tax relief. However at the end of the calculation, HMRC is asking for this to be paid as additional tax. This should be a reduction! To check this I have backtracked and removed the Gift Aid payment and this reduces the tax payable. I also tried increasing the Gift Aid amount (hypothetically - I haven't submitted the return yet) to £10000 and the result was a tax demand for £2500. The number is correct but this should be a rebate, not an additional tax charge.
Has anyone else experienced this problem? Have I done something wrong? I should add that I have claimed this relief for many years and the Self Assessment calculator has always been correct.
Hopefully someone can help?

unholyangel

Did you pay enough tax in the first place? Actual figures might help members work out what the issue is.

KC62

OK - thanks for the steer. We're talking in the region of 60k taxable income and 1k in Gift Aid, so yes, I paid way more tax than the Gift Aid amount.

KC62

I've found the problem - the Self Assessment form was pre-populated with my occupational pension income (and tax paid) but when I filled in the section about pensions the only question I saw was "did you receive state pension?" to which the answer is "no". I then deleted that section without looking at the next page, which is for occupational pensions. The original assessment assumed I had no income at all, so in that case I would have to pay tax on a Gift Aid payment (if HMRC give tax relief to a charity somebody has to have to paid it in the first place). Now I've added my occupational pension back in, the calculation is correct. Thanks to unholyangel for the prompt about paying enough tax in the first place.