My husband had a letter late November suggesting he needed to self-assess due to me receiving child benefit. This is the first we knew about it as our finances are kept separate and he has always been PAYE. This has led to some horrendous realisations about how much we owe, but he filed all the paperwork as soon as he was set up with a link (late December) and we have paid back all we owe plus the interest that was added. Not a small amount. We are now seeing penalties added to his account and some online calculations suggest we will be charged £1600 per year for late filing! Do HMRC always apply these penalties? When do they appear on our account and is the appeal process worth using? As background our son died suddenly in 2022 and our surviving son has had significant health challenges and a big op last year so our minds have not been on tax affairs. No letters were received prior to last Nov. Particularly panicking now as our beloved family dog may have cancer and we are looking at some very expensive treatment. Help!