CGT already paid. Box 22 allows no entry. Please advise.

I am submitting a return for 2020-21 which I have been asked for by HMRC. I paid CGT on a property disposal at the time. The form is calculating that I owe CGT. Less than I have actually paid. The onlinbe help agent suggests that I can enter what I have already paid (in box 22.). Box 22 does not allow me to enter a figure. Please advise.

Hi,

You need to select the section for gains already reported and enter the gain and the tax paid there.

Thank you.