How to pay tax owed according to P800

In August 2023 I received a P800 message saying that I have underpaid income tax for the 2022-23 year, which is correct. However, when I logon to my personal tax account online, I see a box with "You paid the right amount of Income Tax for 6 April 2022 to 5 April 2023". And there doesn't appear to be any way to pay the amount I owe online. How can I pay this outstanding amount? I would rather pay the amount as a lump sum than an adjustment to my 2024-25 tax code. What is the latest date I can pay the amount before my 2024-25 tax code is adjusted? Many thanks.

Hi

As it will already be on your record to be coded, that's why it shows as nil.
You can make payment via your personal tax account and any payments you make between now and the end of March 2024 will change the tax code.
The first codes are due to go out at the end of January 2024 and will show the full underpayment. If you pay in instalments, each payment will produce a new code.

Thank you