THET

It is a funny issue for me as HMRC has repeatedly made mistakes. For the 2023-2024 tax year, my taxable income is £100,900, so the tax due is about £31,000. However, HMRC calculated a tax amount of £530,000 due to backdated pay of about £40,000 plus this year’s income of £100,900. I have already paid about £43,000, but they are asking me for nearly £9,500.26 for the backdated pay. I replied to them that £40,000 is backdated pay and £100,900 is the current taxable income. Therefore, HMRC owes me around £13,000 as I have paid £43,000 instead of £31,000 this year. However, that £13,000 is a similar amount to the tax I need to pay for the recalculated tax for 2021-2022 and 2022-2023. So, the net balance is zero, and I am fine with this. However, HMRC replied that there is no tax due for the tax year 2023-2024, but I still need to pay them around £6,000 for the backdated pay issue, plus the initial £9,500.26. My understanding is if HMRC make mistake for a year ago tax issue based on the information, i can write to HMRC to write off tax. Acutally - the net balance is zero , hospital did the correct calculation already. How can i get help for this discrepancies issue