Double counting for outstanding tax from a previous year paid through this year's tax code

Throughout the year 2023-2024 my tax code was adjusted to pay the tax owed from the year 2021-2022. The amount has already been settled through deductions made from all my paychecks as this debt was included in my new tax code for 2023-2024. However, when filing the return the amount in question is added to the total amount payable this year, as if it were still outstanding. If I submit this result to HMRC, what will happen? Will you require me to make that payment, or will it be adjusted and deducted? How can I ensure that there will be no double counting for the outstanding tax? Thank you.

Hi,
As an underpayment was collected in your 2023 to 2024 tax code then this needs to be included in your tax return. You will not have to pay the underpayment again as on the tax return you declare the tax deducted at source and will receive the credit for the tax dedcuted to collect the underpayment. 
Thank you.