A contractor invoice fails for four reasons: retention nobody explained, variations that never got their own line, daywork without a signed sheet, and a stage described as “works to date”. Here is the invoice that survives a site meeting.
Trade invoices are not retail receipts. On a building job the invoice is a claim against a contract, and the client’s quantity surveyor or bookkeeper will read it looking for the line they are allowed to withhold. That is why a clean invoice matters more here than anywhere: vague wording is an invitation to hold money back.
This guide covers the fields that stop arguments, how to show retention and variations, and where a template stops being enough. If you are invoicing simple one-visit jobs, the plainer Google Docs invoice template is the shorter route.
What actually gets disputed
Four things, over and over.
- Stage descriptions. “First fix complete” means something different to you and to a client who expected sockets energised.
- Variations. Work added in a conversation, invoiced in a lump. The client cannot match the number to anything they agreed to.
- Retention. Withheld without a line explaining what it is, how much, and when it is released.
- Daywork. Hours on an invoice with no signed sheet behind them.
The fields a contractor invoice needs
On top of the normal invoice basics, a construction or trade invoice carries these.
Job and site identifiers
Your job number, the site address, and the client’s purchase order if they issued one. A purchase order number that is missing from an invoice is one of the most common causes of a payment sitting in a holding queue, because their system cannot match it to the order.
The stage, described physically
Not “stage two” and not “works to date”. Write what is now in place: “ground floor first fix: 42 double sockets, 6 lighting circuits, consumer unit installed and tested”. A description a non-trade person can walk around and verify gets paid faster than a percentage.
Variations as separate lines
Every variation gets its own line, its own reference, and the date it was agreed. If you agreed it verbally, write “agreed on site, [date], confirmed by [name]”. Never roll variations into the main contract sum. The moment they are absorbed, you have lost the argument about whether they happened.
Retention, shown openly
If your contract holds retention, show it as a deduction line with the percentage, the amount held this time, and the total held to date. Then state the release conditions in one sentence. An unexplained deduction looks like a mistake. An explained one looks like a contract being followed.
Daywork with a sheet reference
Hours worked, rate applied, and the reference of the signed daywork sheet. If there is no signed sheet, do not invoice it and expect to win. Chase the signature instead.
Tax and status statements
Whatever your jurisdiction requires: tax number, reverse charge wording, CIS statement, VAT. Do not improvise these from memory. Ask your accountant once, then keep the exact wording in your template so it is identical on every invoice.
Stages, milestones or monthly valuation
Three ways to bill a job, and they suit different clients.
Stages work for residential jobs where the client understands the sequence: strip out, first fix, second fix, snagging. Milestones work for commercial clients who think in deliverables. Monthly valuation suits longer jobs where the client’s finance team expects a regular cycle.
Whichever you use, the invoice should let the client calculate the percentage complete without asking you. That single property, verifiable from the page, prevents most stage disputes.
Drafting it in ten minutes
Give the model your site note, in your own shorthand, and let it produce the invoice lines. The rule that matters: it may only use facts you gave it. No invented quantities, no made-up rates.
You are turning a site note into invoice lines for a contractor. SITE NOTE [write what you actually did, in your own words, including room names and numbers] CONTRACT - Contract sum: [amount] - Stages agreed: [list] - Retention: [percentage, release conditions] - Variations agreed so far: [list with dates] Rules: 1. Produce one invoice line per distinct piece of work, each with quantity, unit, rate and amount. 2. Separate the contract work from the variations. Variations get their own section with their reference and agreement date. 3. Add a retention deduction line showing this period's amount and the total held. 4. If my site note is missing a quantity or rate, write [MISSING] instead of guessing. 5. Total the invoice, then show the amount payable after retention. Output as a plain list I can paste into my invoice template.
Explaining a variation without a fight
The argument usually starts because the client remembers a conversation differently. Restate what was agreed, price it, and let them see the number before the work lands on an invoice.
Write a short variation notice for a client. WHAT CHANGED [job, what was added or altered, why it was needed] PRICING [hours or materials plus rate, and the total] Rules: - Confirm the date and who agreed it, in one line. - State the price before describing the benefit. - Ask for a one-line approval reply. - Keep it under 120 words, plain English, no blame and no hedging.
The invoice that has gone quiet
Once a contractor invoice is thirty days old, the problem is usually not refusal, it is routing. Someone is waiting for a purchase order number, or the invoice went to the wrong inbox. Ask a routing question, not a payment question.
Write a follow-up about an unpaid contractor invoice. DETAILS - Invoice number, date, amount - Due date and days overdue - Anything I know: no PO received, sent to wrong address, query raised Rules: - Assume it is stuck in their system, not that they are refusing to pay. - Ask one specific question that unblocks it: is a PO needed, who approves it, where should I resend it. - Offer to reissue with any reference they need. - Under 110 words. No threats, no exclamation marks.
Where a template runs out
A document template holds wording. It does not hold your job numbers, your variation register, or last month’s retention total. Once you are past a handful of live jobs, a spreadsheet or a generator with a job list does that job better, because the numbers carry forward rather than being retyped.
If cash is the problem rather than paperwork, the pattern in how to chase an overdue invoice is the thing to fix first. And if you are still settling what a job should cost, work backwards from the job profit calculator and the hourly rate calculator before you write the invoice.
Frequently asked questions
Should I include a purchase order number on a contractor invoice?
Yes, whenever the client issued one. Missing purchase order numbers are a common reason invoices sit unpaid in a client’s approval queue, and adding it costs you nothing.
How do I show retention on an invoice?
As a separate deduction line: the percentage, the amount withheld this time, the total withheld to date, and the release conditions in one sentence. Never net it off silently inside the total.
Can I invoice for work with no signed daywork sheet?
You can invoice it, but expect to argue. Signed sheets are the evidence that makes daywork recoverable, so chase the signature the same week rather than at invoice stage.
What is the best stage description on a trade invoice?
A physical one the client can verify on site: what was installed, how many, and what was tested. Percentages and stage labels invite disagreement; installed quantities do not.
Should variations go on the same invoice as contract work?
Same invoice, separate section. One document keeps the paper trail simple, but the variation lines need their own reference and agreement date so they never disappear into the contract sum.
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Last reviewed and updated on November 12, 2026.
