Subcontractor bills you can certify without a dispute
Subcontractor billing causes more site arguments than any other payment. How to scope, measure and certify subcontracts so every bill is checkable in a single afternoon.
Every contractor knows this argument. The subcontractor submits a bill for 60 percent complete. You walk the site and see 40. Both of you are sincere, both of you are annoyed, and the work slows down while you negotiate something that should have been arithmetic.
The cause is almost never dishonesty. It is that the scope was described in a conversation, the way progress is measured was never written down, and the running total lives in two different heads. Fix those three records and the bill becomes checkable.
What the argument is actually about
| The bill says | You are thinking | The record that is missing |
|---|---|---|
| Blockwork 60 percent complete | Complete of what, exactly, which walls | The scope lines with quantities from the BOQ |
| Extra excavation, 3 days | Nobody instructed that in writing | A dated instruction before the work started |
| Previous payment not adjusted | We paid an advance in March | A certified-to-date ledger both sides have seen |
| Full rate for the slab | The slab has honeycombing at two columns | A joint measurement note with defects listed |
A subcontractor bill is not a claim to be negotiated. It is a measurement to be checked.
The three records that prevent most disputes
1. Scope written against BOQ lines
Do not write "grey structure labour" on the subcontract. List the BOQ lines it covers, with the quantities from your own estimate: blockwork in square metres, plaster in square metres, concrete in cubic metres. If a line is excluded, say so in the same document. The exclusions cause more fights than the inclusions.
2. A measurement method agreed in advance
For each line, one sentence on how it is measured: plaster measured net of openings above a stated size, blockwork measured per drawing with no doubling of corners, concrete per pour card. This feels fussy on day one and saves a week of argument at every billing.
3. A certified-to-date total both sides can see
After every billing, one page: quantity certified to date per line, value certified to date, retention held, paid to date, and the balance. The subcontractor signs it or notes the disagreement on it. The next bill starts from that page, not from memory.
Never certify from chat photos alone. Photos show that work exists, not how much of it exists or whether it meets the specification. Someone measures on site, with a tape, on a stated date.
A certification routine that takes an afternoon
- 1
Walk and measure together
You and the subcontractor, same day, same tape. Agree each quantity on the spot and note defects separately so they do not contaminate the measurement.
- 2
Price from the subcontract rates
Certified quantities times the agreed rates, not the BOQ rates you priced to the client. The margin between the two is yours and should never appear in this document.
- 3
Deduct retention and advances
Retention percentage per the subcontract, less any advance recovery due. Advances forgotten at billing time are the most common source of overpayment.
- 4
Issue the certificate, not just the payment
A dated page with the quantities, the value, the deductions and the net payable. Payment follows the certificate, and both sides keep a copy.
- 5
Update the running total
Certified to date, paid to date, retention held, balance to complete. This page is the opening position for the next billing.
Fix one billing day per month per site and keep it. Subcontractors who know when measurement happens stop lobbying for interim assessments, and your engineers can plan the walk instead of being ambushed by it.
Labour-only and with-material need different controls
| Point | Labour-only | With material |
|---|---|---|
| Rate risk | Yours on material price movement | Theirs, unless the contract allows escalation |
| Wastage | Your loss, so you control issue quantities | Their loss, so you check quality instead |
| Measurement | Progress against scope lines | Progress plus delivery dockets reconciled |
| Biggest failure | Idle labour claimed as working days | Inferior material substituted silently |
On labour-only jobs, reconcile material issued against work done. If the cement issued builds half again as much blockwork as measured, the difference is sitting somewhere: wasted, stored, or walked away. On with-material jobs, check deliveries and test results instead, because the quantity incentive runs the other way.
When you already disagree
- 1Stop work on the disputed item only, not the whole site. A full stop converts a measurement disagreement into a delay claim.
- 2Re-measure jointly within 48 hours, while the work is still visible. Every week of delay buries evidence under the next activity.
- 3Pay the undisputed part immediately. Holding the whole bill hostage over one line tells every other subcontractor how they will be treated.
- 4Record the disputed line as disputed, with both measurements on one page. Most disagreements settle once the two numbers are on the same sheet.
Nuvailo tracks subcontracts against the same BOQ lines as your client billing: scope lines, certified quantities, retention and the running total per subcontractor. The certificate is then a view of the record rather than a document rebuilt each month.
Questions this raises
Should we hold retention on labour-only subcontracts?+
Yes, though often at a lower rate than with-material work. Retention is not only about defects, it is the lever that brings the subcontractor back for snagging. Release it against a snag list signed off, not against a date alone.
What if the subcontractor refuses joint measurement?+
Measure without them, photograph the tape readings, and issue the certificate noting their absence. A one-sided measurement done transparently beats a joint one that never happens.
How do we handle daywork claims?+
With a signed daily sheet: date, names, hours, and what was done, signed the same day. Daywork reconstructed at billing time is indistinguishable from invention, even when it is genuine.