Unused residential finance costs on SA

Can anyone help me to understand when this box would be completed. I understand the residential finance costs box and have input the full amount of interest I have paid on a btl mortgage but do not understand when the unused box would be completed. Is it a calculation I would need to do or in what circumstances would it be applicable. Sorry for asking what may be a simple answer!

Hi ,
 

If you had a tax year when you you did not make much rental profit but you had your usual finance costs you can carry forward residential finance costs to use in year that you made a profit. The tax reduction applies to each property business and cannot create a loss. Thank you .

Thanks for reply. I have made less profit for 23/24 so I think it might apply. How do I calculate the amount to carry forward. Generally speaking my profit for previous years is £2k ( not using any finance costs in that calculation of profit) for 23/24 its approximately £1k year, next year 24/25 it will be even less due to long periods without a rental income. How do I work out what to put in the unused finance box for 23/24. Thank you

Hi,
Thank you for your question.
If your profit from property income for example £2K your finance costs are £2500. You can use £2k to cover the profit and the unused finance costs can carried forward to the following year.
Furthermore, financial cost is only relieved at a Rate of 20%.
I would suggest that when completing your Income from property page, of your tax return, you contact us by telephone, and we will walk you through this aspect.
Alternatively, you could follow the guidance at: 
Tax relief for residential landlords: how it's worked out - GOV.UK (www.gov.uk) and
UK property notes (2022) - GOV.UK (www.gov.uk) 
Thank you.