Here is a problem put to me that I can't answer, being retired.
A taxpayer made monthly contrubutions in 2015-2016 , 2016-2017 and 2017-2018 to an appeal, which failed to achieve its objects. Rather than come up with a cy-pres scheme the Charity Commission authorisised the charity to repay the contributions.
These had been subject to gift aid. I have dissuaded the taxpayer from asking HMRC to work it out, as they might seek to reopen the relevant years , on the grounds he has had an unexpected benefit, namely his money back. If he had to reopen earlier years he could relate back to 2017-2018 if he claimed by 31/01/19, but not earlier years. I would have suggested he declare the returned contributions as income in the year it was received, with a white space declaration explaining what it was. He could then pay them into another charity, thus covering the income declared, and avoiding any higher rate liability. The enquiry window would close a year later.
I couldn't find anything in HMRC's manuals, although SAM112040 tells their officers how to get their money back if the overrepayment arose through taxpayer error. He didn't make an error. And no amount of googling has come up with and answer.
Has any reader got any wisdom on this one?