How to track payment due against purchase order funds

Why this matters for contractor billing

A purchase order is often treated as a simple budget number, but the real operational question is whether approved work and upcoming invoices are still covered by the funds that remain. That becomes difficult when timesheets, approvals, invoice drafts, and PO balances all live in different places.

If you only check the original PO value against invoices already sent, you will miss exposure building up in approved timesheets and unbilled work. By the time finance notices, the team may already have delivered more work than the purchase order can support.

• Approved timesheets may already represent committed revenue before the invoice is raised.
• Pending submissions can hide more future billing exposure.
• Project managers may assume funds remain because the invoice ledger has not caught up yet.
• Clients can dispute overruns if there is no clear audit trail against the PO.

The three numbers you need to track separately

To manage purchase order usage properly, separate the original allocation from what has already been billed and what is now due based on approved work. Those are related numbers, but they are not the same.

Once those figures are visible together, overrun risk becomes obvious much earlier.

• Allocated funds: the total value approved on the purchase order.
• Billed value: invoices already issued against that purchase order.
• Payment due or committed value: approved work that is ready, or almost ready, to be invoiced.

Where teams usually go wrong

The most common mistake is relying on invoices alone as the source of truth. In fast-moving contractor environments, invoice creation usually happens after time approval. That means the true financial position changes before the accounting record does.

Another common mistake is tracking the purchase order in a spreadsheet that is updated manually at the end of the month. That delay is exactly when overruns happen.

• Timesheets are approved, but nobody updates the purchase-order tracker immediately.
• Multiple contractors charge against the same PO with no shared live balance.
• Managers cannot distinguish submitted time from approved, invoice-ready time.
• Finance sees the issue only after the invoice pack is prepared.

A simple operating model that works

A better model is to treat approved time as committed value against the purchase order, even before the invoice is sent. That gives delivery and finance teams a more realistic view of exposure.

In practice, each contract or work stream should point to a purchase order, approved timesheets should roll into a committed total, and the system should show the remaining balance after both billed and approved work are considered.

• Link each contractor engagement or contract to the correct purchase order.
• Update committed value when time is approved, not only when the invoice is issued.
• Show remaining balance in real time to delivery and finance users.
• Flag thresholds before the PO is exhausted, not after.

What to report each week

Weekly reporting is usually enough to prevent unpleasant surprises. The key is to make the report operational, not purely financial. People need to see how much of the purchase order has been billed, how much is already committed through approvals, and what balance remains for upcoming work.

That makes renewal or extension conversations easier because the account team can speak with evidence rather than estimate from separate spreadsheets.

• Original PO value.
• Total billed to date.
• Approved but not yet invoiced value.
• Submitted but not yet approved time if you want an early warning layer.
• Remaining available funds after committed charges are taken into account.

How BillByTime helps

BillByTime is built to connect timesheets, approvals, contracts, and purchase orders in one workflow. That means approved work does not disappear into an inbox while someone updates a PO tracker later. Managers can see what has been worked, what has been approved, and how that affects remaining purchase-order coverage.

For contractor teams, this closes the gap between delivery activity and billing visibility. You do not have to wait for month-end spreadsheet reconciliation to understand whether the PO is still healthy.