Use Schedule Payments in Payables
A relatively new feature in Dynamics GP is the option to take a payables transaction and split it into multiple payments. This is great for things like loans or leases. The entire transaction can be entered into payables and then paid in installments while accounting for interest.
To set this up, click Purchasing in the Navigation List on the left and select Scheduled Payments. Use the lookup button to select an existing payables transaction to schedule. Most of the rest of the screen is straightforward with the schedule date, total to pay over time, simple or compound interest, an interest rate and invoice dates. The Calculate button at the bottom will calculate the new payment. The amortization button shows the amortization scheduled.
Then there are three accounts at the bottom. Essentially the accounting for this removes the amounts from payables and puts them in another liability account. Processing the scheduled payment moves the liability back into payables and applies the interest expense. The accounts (in order) should be your normal payables account, a different liability account since these are no longer immediately payable and an interest expense account.
Click Post to create the "scheduleTo process" scheduled payments: Purchasing >> Routines >> Post Scheduled Payments.