20% Tax relief on residential property income

Last tax year I wasn't aware of the 20% tax relief on residential property income, and so didn't include any financial costs. Looking at last year tax calculations, it appears that no relief was taken into account at all. - Is it possible to carry forward the mortgage interest from last year (2021/22) to this year (2022/23)? - If so, do I just add the mortgage interest from April 2021 to April 2022 to the "Unused residential property finance costs brought forward" box? and; - mortgage interest from April 2022 to April 2023 to the"Residential property finance costs" box? Many thanks.

Hi CheddarCat,
No amend your 2021-22 return online before 31/01/2024 to include the residential finance costs in box 44. 
Thank you.