Where to enter previous tax payment for 2021-22 year?

I received a P800 in summer 2022 prior to registering for self assessment. As a result, tax owed for 2021-22 was deducted from a refund I received for a previous tax year. Where do I enter this tax payment already made for 2021-22 on my 2021-22 self assessment?

Hi,

This will be at underpaid tax and other debts, page 2 of 2.

It refers to tax due collected in a later years code, but as you have paid it already, show it there to be given the credit for it.

Thank you.