Where to put mortgage info

I am not sure where to put in my mortgage. I can work out on paper what cgt is due but at loss on where to include my mortgage. I tried saying a cost but that didnt seem right and didnt give me the right tax. I also subtracted mortgage from buying and selling price and that didnt work out either. Am i missing something? V

Hi,

Your mortgage is not an allowable cost for working out capital gains.

Thank you.