Unsure which SA needs to include underpaid tax for previous year

I received a notice in August 2020 that I paid too little tax in 19/20 tax year, and that the £319.20 owed will be collected from following April through PAYE. My PAYE coding notice in for 21/22 showed this adjustment ‘Less adjustment for tax you owe (earlier year)’ £798’. I had entered this on my 20/21 SA under but I’m now inclined to think that was a mistake - due to the date of the letter it is awfully confusing. Could I confirm that I need to include this on my 21/22 return instead, ie as follows and amend to leave these sections blank/£0 for the 20/21 return? Underpaid tax and other debts 7. Amount of underpaid tax for earlier years included in your tax code for 6 April 2021 to 5 April 2022 (from your PAYE Notice of Coding): £ 319.20 8. Amount of estimated underpaid tax for 6 April 2021 to 5 April 2022 to be included in your PAYE tax code for 6 April 2022 to 5th April 2023 (from your PAYE Notice of Coding): £ 0.00 9. Amount of outstanding debt included in your tax code for 2021-22 £ 0.00

Hi,

The returns need to have the correct amount for each year on them. If you are unsure if 2020 to 2021 was completed correctly, please contact our Self Assessment team and we can review the return.

Self Assessment: general enquiries

Thank you.