How to Claim 20% Mortgage Interest Tax Credit

I'm completing my 21-22 Self Assessment and have given the annual amount for my BTL mortgage interest in the box ' Residential Property Finance Costs' however it is not appearing in the tax summary and the 20% tax credit doesn't appear to be included in the calculations. Can anyone help? If it doesn't get included/deducted here, then how is the 20% tax credit paid or taken into consideration? All I can find reference to on the web is that you can claim a tax credit but nowhere does it state how this is factored in or paid to you.

Hi
Thank you for your question.
You are correct that mortgage interest can be claimed by using Box 44 "Residential Property Finance Costs" on the SA105 property supplementary page.
I would advise that if your calculation is not showing the finance costs as a reduction to your overall tax liability, to submit the Tax Return and contact the Self-Assessment Helpline on 0300 200 3310 after 72 hours of submission, who may be able to amend the required amendments.
Regards.