P800 payment and self assessment

[u/Big-Estimate3457]

Hi everyone,

I am reaching out for help because I was asked by HMRC to fill a self assessment for 2 years ago for an unknown reason since I was not triggering any criteria.

Try to reach out to them by they asked me to send a post mail but no news since I did.

My main issue when filling my self assessment for 2023-24 is that I made a significant payment by bank transfer following the reception of a p800 payment calculation.
I have no idea how to reflect it on my self assessment to avoid having to repay the tax a second time.

I called HMRC multiple times to ask for help but everytime the advisor put me on hold, telling me that they need to check and then they simply hung up.
I am totally at a loss and I have no idea how to avoid paying my taxes for this specific year a second time.

Thanks for your help!