I have a table of accounts which includes the value starting amount and start date. I have another table of payments which includes the payment date, period (this is number of months from start date) and payment amount.
I need a pivot chart that works out the sum of the original amount for each period. To get to this it must subtract the sum of any payments from previous periods from the starting amount.
I've attached an example and I've put a simple sum(Payment Amount) in where I would like my rolling total to be.