The quick answer
To represent a monetary services authorization through quantity, use a non-inventory purchasing item with one authorization unit per dollar and Rate 1.00. Bill each installment by changing the bill's quantity while retaining that rate. Compare ordered and billed quantities to calculate remaining units. Separately reconcile the saved bill amounts against the original authorization. Here, 7,500 billed units correspond to 7,500.00 USD because the rate stays at 1.00 and there are no adjustments. In this example, 12,000.00 − 3,000.00 − 4,500.00 = 4,500.00 remaining. This tracks a quantity-based authorization; separate controls must enforce any hard spending limit.
The person and operating-company names in the screenshots are fictional example data.
Before you start
Use an approved PO, an open bill posting period, and a role that can view purchase orders, create vendor bills and inspect Related Records. The example item is a non-inventory item for purchase with Can be Fulfilled/Received cleared. In this configuration, no item receipt is created. Confirm the item receiving configuration and your purchasing process before applying the pattern elsewhere. Item setup and approval configuration are prerequisites; approval affects whether the PO can be billed, separately from whether an item is receivable.
PO7400 represents a 12,000.00 USD purchasing authorization for Orchard Advisory using 12,000 quantity units at 1.00 USD each. This is an agreed tracking convention, not a native monetary budget or guaranteed spending limit. A unit represents one US dollar of authorization. It does not mean an hour, physical stock or a completed deliverable. If invoices are based on hours at a stable rate, genuine hours may be the more useful quantity.
The bills use Example Supply US, US Dollar and 2000 Accounts Payable in Oct 2026. This reconciliation excludes tax, freight, credits, exchange-rate effects, closed lines and approval exceptions. Review those separately in your account.
1. Review the original authorization
Open PO7400. Confirm its approval and that Bill is available; displayed status labels depend on configuration. Check the original Total 12,000.00.
On Items, verify Billed 0 and Quantity 12000. The Rate 1.00 makes the line Amount 12,000.00. Keep that meaning of quantity explicit when AP processes each invoice.
2. Save the first installment
Choose Bill on the PO. In this walkthrough, the transformed bill opens with 12,000 currently unbilled units. Review the copied quantity; defaults can depend on transaction state and account configuration. Enter supplier reference OS-7401. Edit the existing Items line, change Quantity to 3000, retain Rate 1.00, and choose OK to commit the line.
Verify Amount 3,000.00, then save the bill.
3. Check what the first bill consumed
Reopen PO7400. The original quantity remains 12000 and the PO total remains 12,000.00. Its Items Billed quantity is now 3000. That leaves 9000 quantity units. At this example's unchanged 1.00 USD per unit, the corresponding amount is 9,000.00 USD. Use quantities and related saved transactions for this reconciliation; the displayed PO status may vary by configuration.
4. Save the second installment
Choose Bill again. In this walkthrough, the second transformed bill opens with the remaining Quantity 9000 at Rate 1.00. Confirm the copied quantity and rate; defaults depend on transaction state and account configuration.
Enter OS-7402. Edit the line, reduce Quantity to 4500, retain Rate 1.00, and choose OK. Verify Amount 4,500.00, then save. Check the second saved bill's reference and amount.
5. Reconcile the two bills
Reopen the PO and check Billed 7500 against the original Quantity 12000. Billed here is cumulative billed quantity, not a monetary balance. It is numerically equal to dollars only because the rate stays at 1.00 and this example excludes adjustments.
Open Related Records > Receipts & Bills. Verify the saved bills OS-7401 for 3000.00 and OS-7402 for 4500.00. Subtract their amounts from the original authorization:
12,000.00 − 3,000.00 − 4,500.00 = 4,500.00 remaining.
6. Inspect the remaining quantity without saving a third bill
Choose Bill once more. In this walkthrough, the unsaved transformed bill shows Quantity 4500, Rate 1.00 and Amount 4,500.00. Verify the copied values; this is not a guaranteed native monetary remainder field.
The walkthrough ends on this unsaved bill. Do not save it. No payment or item receipt is created. The result is a reconciled remaining authorization, not a new payable or a guarantee that an overage will be blocked.
Common questions
Why can a quantity-one services PO become fully billed after a smaller invoice?
If the vendor bill retains Quantity 1, it can consume the PO line's entire ordered quantity even when the bill's rate or extended amount is lower. A lower billed amount alone does not preserve an unbilled quantity. Use a quantity convention that supports installments, and verify the bill quantity before saving.
Should services quantities represent hours or dollars?
Use hours when invoices measure hours at a stable agreed rate. A monetary authorization can instead use currency units at rate 1.00, as shown here. Explain that convention to buyers and AP so units are not mistaken for hours, inventory or delivered work. This is a manual quantity-and-rate convention, not a special monetary-budget mode.
Is the PO total supposed to fall after each bill?
No. This example preserves the original PO total of 12,000.00. Cumulative billed quantity shows the quantity consumed, while the related vendor bills show saved billed amounts. Here, those figures correspond because the rate is fixed at 1.00. Calculate the remaining authorization from those inputs; do not treat the original PO total as an automatically reduced balance.
Does this create a native Remaining Amount field or enforce a hard budget?
No. The remaining amount is a reconciliation of the original authorization and saved bills. The next bill's remaining quantity supports it in this fixed-rate example. A saved search or custom field can present a defined calculation; preventing overages requires separately configured and tested controls.
What can make the simple remaining calculation differ from the next bill?
Other bills or credits, closed lines, approval and transaction-state rules, tax or freight treatment, unit conversions, rate changes and currency effects can change the billable remainder or the amount counted against the authorization. Billed quantity may not reconcile directly to monetary spend when the rate, unit, currency or line treatment changes. This example has none of those adjustments. Define their treatment before using the figure as a purchasing control.