I am creating a report for a bank to provide an account history for customers. I have a relational download with 3 tables. The first table is the customer table, the second is the account table and the third table is the transaction table. The transaction table includes principal, interest and changes to interest rates. So far I've created a form with the customer and account information and then a subform with the transaction information. My issue now is that in order to make this useful I need to include two additional columns in the subform, based on the transactions listed, that include a running balance and can calculate the interest accrued for the specific time period between transactions. My question, is it possible to have a running balance that would increase and decrease based on the principal transactions posted? I'm willing to enter a starting balance, if necessary. Any help would be greatly appreciated!