Using a cash isa to pay interest off on an equity release mortgage - how to organise this?

Orange_Balloons

I have a cash isa that pays 5.17% daily interest as recommended by Martin Lewis.  I also have an equity release mortgage.  I do NOT need to pay interest on the equity release, but interest will accrue at 5.5% also on a daily interest.
I want to pay the interest on the equity release, every year, so that on my demise only the original sum loaned will need to be paid back by my children, or possibly a bit less. I can pay only 6 payments a year off the equity release. 
Is it better for me to save up, in the cash ISA, the amount of interest that would accrue on the equity release, in a year, and then pay that interest just before the end of that year (so in year 2 and so on it would go back to the original sum), or should I make 6 payments using my savings in the cash ISA? Which gives me the best value?

eskbanker

As the mortgage has a higher rate than the savings, it'll be financially advantageous to pay it off as early as possible rather than building up savings in the ISA.  Note also that most variable rate ISAs are dropping their rates, so you may not be getting 5.17% for much longer anyway....