Sorry if this is long but want to tell the whole story. I have been claiming child tax and working tax credits since 2016. I got an inheritance and tax credits operate differently than UC in that there is no capital limit, they only care about interest earned above £300. I know a lot of people disagree with this but that’s a whole other thread. Anyhow, when I renewed for tax year 2019-2020 I checked my interest and didn’t declare it as it was less than £300. My mistake though was I forgot that renewals are based on the previous tax years income. So I phoned the bank to check how much interest I made tax year 2019-2020 and it’s £601! So I phoned HMRC to tell them my mistake and that I’ve probably been overpaid that whole year! They said I have to write to them, explaining as they can’t sort it over the phone as it’s too long ago so I posted the letter today. I feel better that I have been honest and admitted to my mistake but I am panicking about what they will do. I hope I’m not penalised too harshly. Anyone on MN done similar and what happened? I of course am willing to pay any money I shouldn’t have got back but I hope they don’t take me for fraud. If you have made it to the end, thankyou and please don’t be too hard on me because I am already furious with myself