In short: I forgot to notify HMRC when I stopped making personal pension contributions in 2018, so my tax code will have been incorrect and I will have underpaid for several years.
I'd like to know whether there is anything else I can do now to try and rectify, and whether it's likely they will impose a penalty?
My job could be affected by a tax penalty, so I'm rather worried.
Longer version; I used to file a tax return because I had minimal investment income (under £100) and claimed relief on personal pension contributions. I was and still am on PAYE and had no other income. In 2018, HMRC told me I didn't need to file more returns. Obviously, it was my responsibility to notify them when something changed, but this meant I just didn't think about it. Later in 2018, I took the opportunity to transfer my private pension funds into my employer's scheme, and stopped making contributions, but I forgot to tell HMRC.
It came to light this year when I received a notice of tax code change, and the personal allowances were all set out.
Since then I have:
a) filed a tax return for 2022-2023 and immediately paid the calculated liability:
b) sent a letter recorded delivery to the PAYE team setting out the full figures;
c) used the online PAYE notification route to notify a change in the information my tax code is based upon - this form only relates to 2022-2023 but I included the information that it dated back to 2018.
Is there anything else I should do now? Do you think there will be a penalty?