Trying to auto deduct expenses each month

I'm trying to have a starting monthly amount (Cell B10 $33,526) and have it reduce X amount (Cell C10 $628.83) every month on a set day (Cell E10 $32,869.95). While I've been able to get it to a point of reducing that amount on the 1st day of the month, I need cell E10 to replace the starting monthly amount in cell B10 and I haven't been able to figure that out as it ruins the formula since it needs something to reference.

I am trying to do this without having to list each month out if possible.

Thanks,

Josh