SumIt mirrors BILL in two steps, the same way you'd think about it on paper: When a bill is approved in BILL, SumIt books the invoice: debit the expense (or whatever GL account it's coded to), credit Accounts Payable. The payable shows as unpaid. When you pay it in BILL, SumIt books the payment: debit AP, credit cash, and marks the payable paid. Example: A $4,000 legal invoice comes over from BILL → SumIt records DR Legal Expense / CR AP, unpaid. Two days later, you pay it in BILL → SumIt records DR AP / CR Cash, paid. You never opened SumIt to make either entry. That's the "no rework."