Mortgage question

cheesesarnie

Hi...

have been overpaying reasonably well against mortgage which has just dropped on nationwide SRV (looking to move to tracker shortly)...

I've been thinking that one day in the next couple of years we might rent out this property & I think if the mortgage was bigger (ie. without the overpayments) we would be able to offset more interest against the rental income.....all the while the continued overpayments could be sat in a cash isa at a rate close/above the mortgage rate [we dont use ISA allowance currently]

does this scan?....

I also wonder, is ISA interest calculated daily like my mortgage?....this could work against the plan if not..

thanks for your help.