The short version. To write a change order: describe the scope change specifically, price it at your normal markup, state the schedule impact in calendar days, carry the running contract amount (A the original contract, B approved to date, C the subtotal, D this change, E the new contract amount), say when it is payable, and get both signatures before the crew starts. Then write the row on your log the same day.
The job below is an illustrative worked example — every date and figure is invented. This is a general explanation of a business document, not legal advice; residential construction is regulated at state and often city level, so check your own state’s home-improvement statute and have a construction attorney read your contract documents once.
The moment a change order starts
You are a few weeks into a bathroom remodel. The subfloor is open, the tile has not gone down yet, and the homeowner walks in and says: while it’s open like that, could we do heated floors?
That sentence is where the money is won or lost on a remodel. Say yes without paper and you have just agreed to an afternoon of unpaid electrical work, a permit amendment nobody budgeted for, and a completion date that has quietly moved. Say “let me write it up” and you have a document that gets signed and paid.
Here is that change order, written end to end.
Step 1 — Stop before you build it
The single most expensive habit in the trades is doing the work first and papering it afterward. The paper is the same either way; the reception is not. A change order signed before the crew starts is an instruction. Signed after, it is a bill, and it gets treated like one.
Several states go further and require changes to a residential home-improvement contract to be in writing and signed by the homeowner before the changed work begins — California’s Bus. & Prof. Code § 7159 (opens in new tab) makes a change order part of the contract only if it is signed first — and an unsigned extra can be unenforceable as part of the contract no matter how clearly the customer asked for it. Some states still leave you other grounds on which to pursue payment, but that is a slower, less certain and more expensive route than a signed page.
The sentence that makes this easy, and that costs you nothing:
“Happy to do that — let me write it up so you can see what it does to the total and the finish date, and I’ll bring it back in the morning.”
It is not a refusal and it is not a negotiation. It moves the conversation from the driveway onto a piece of paper.
Step 2 — Describe the change specifically
Write it so that someone who was not on site could tell what happened. Compare:
| Filled in thinly | Filled in so it is worth having |
|---|---|
| Add floor heat | Supply and install 40 sq ft electric floor-heating mat under the new bathroom tile, on the existing subfloor, with a programmable thermostat set beside the light switch |
The second one names the area, the substrate, and where the control goes. A year later, that is the difference between a settled question and a disagreement.
The line items on one change order
A change order records one change, and it can have several lines — including deductions. Ours has three:
| The change | Add / Remove | Amount |
|---|---|---|
| Supply and install 40 sq ft electric floor-heating mat under the new bathroom tile, on the existing subfloor, with a programmable thermostat set beside the light switch | Add | $1,610.00 |
| Dedicated 20-amp circuit from the panel to the thermostat, including permit amendment and re-inspection | Add | $395.00 |
| Uncoupling membrane priced in the original scope, no longer needed under the heat mat | Remove | -$140.00 |
That third line matters more than it looks. Crediting back what is no longer needed is most of why a customer signs the other two without arguing — and a change order file that only ever goes up convinces nobody.
Step 3 — Price it like a job, not a favor
Price the change the way you priced the original: the labor, the material, the disruption to the sequence, and the return trip. Use the same bid markup — scope creep is where margin leaks, and a change priced at cost is a discount you did not decide to give.
Two things people routinely absorb and should not:
- Permits and re-inspections. Our second line is $395 for a dedicated circuit including the permit amendment and the re-inspection. Absorbed, that is half a day of somebody’s time given away.
- Rework. If a selection changes after the thing it affects has been built, the redo is part of the change, not a goodwill gesture.
Step 4 — State the schedule impact in days
This is the line free change-order forms most often leave blank, and leaving it blank is why customers are surprised in May by a date that moved in April.
| Schedule line | Value |
|---|---|
| Calendar days this change adds | +4 |
| Completion date before this change | May 8, 2026 |
| Revised substantial-completion date | May 12, 2026 |
Write the days even when the answer is zero. Two days on each of six change orders is nearly two weeks, and a completion date that slid without anyone saying so is a recurring reason a customer starts paying late.
If part of the wait cannot be known yet — a special-order item with no confirmed lead time — say so on the form rather than guessing, and issue a schedule notice once it can be known.
Have the schedule conversation before the price conversation. It is the harder one, and it goes better first.
Step 5 — Carry the running contract amount
Here is the part that separates a change order from an invoice for extras.
Most free forms record the change and its price and stop. The customer signs $1,865 in isolation, keeps $21,450 in their head, and is genuinely surprised at the end. A change order that carries the running contract math fixes it in five lines:
| Line | What it is | Where it comes from | Amount |
|---|---|---|---|
| A | Original contract amount | from the work authorization | $21,450.00 |
| B | Change orders already approved | from the change order log | $1,180.00 |
| C | Contract amount before this change | = A + B | $22,630.00 |
| D | This change order | from the lines above | $1,865.00 |
| E | NEW CONTRACT AMOUNT | = C + D | $24,495.00 |
Line E is the number the customer signs. Not the delta — the total. They have now agreed to $24,495 about a month before the invoice that would otherwise have started an argument, and the final payment has something concrete to reconcile against.
Copy line B off your register rather than from memory. The whole thing only works if the two agree.
Step 6 — Say when it is payable
An amount with no date attached is a wish. State it plainly: payable with the tile-complete stage payment, due April 29.
Unless you say otherwise, the sensible default is that an addition is payable with the next stage payment that falls due after the change order is signed, and a deduction is credited against the final payment. Everything else in the original contract — the warranty, the payment terms, the exclusions — carries over to the changed work unchanged.
Step 7 — Get both signatures, then hand over a copy
Both parties sign, dated, before the crew starts, and the customer gets their signed copy the same day. The federal Cooling-Off Rule (16 CFR Part 429 (opens in new tab)) runs its three business days from the date of the transaction and requires you to hand over a copy of the contract carrying the required cancellation notice, plus two copies of a cancellation form; several state home-solicitation statutes go further and do not start the clock until the customer actually has their copy and that notice.
Then photograph the area the change affects, before you touch it. On a change order the pictures matter more than on the original scope, because a change is by definition the thing nobody planned for.
Step 8 — Write the row on the log
Same day, while you are still holding the pen. One row per signed change order, on one register per job:
| CO # | Date signed | What changed | Add / deduct | Days | Running contract amount |
|---|---|---|---|---|---|
| CO-001 | Mar 19 | Relocate towel warmer circuit | $310.00 | 0 | $21,760.00 |
| CO-002 | Apr 2 | Upgrade shower valve to thermostatic | $870.00 | +1 | $22,630.00 |
| CO-003 | Apr 14 | Electric floor heat, dedicated circuit, membrane credit | $1,865.00 | +4 | $24,495.00 |
That last cell is line B of the next change order, and it is the page you put in front of a customer who says the final bill came out of nowhere. Total the days column too — that is how much the change orders moved the finish date. Add any delay days from your schedule and delay notices on top of it to get the honest completion date.
Three rules to remember (not steps)
- Nothing outside the scope gets built before it is signed. Not small things, not free things, not favors. A favor you did without paper is a favor the customer will not remember was one.
- Every change order carries a schedule line, even when the answer is zero days.
- The log gets its row the same day. A register nobody updates is a filing index, not a register.
When the customer pushes back
Some will. The answer is almost never to argue about whether the change is a change — it is to go back to the exclusions on the original work authorization. A change is only a change measured against a scope that said what it was not. That exclusions list is the clause people most often delete for feeling unfriendly, and it is the clause every change order you ever write leans on.
If the pushback is about an allowance — the tile that came in at twice what was budgeted — the same logic applies, plus one extra point most customers have not considered: an allowance covers the material, not the labor to install something heavier, larger or differently rough-in’d than what was priced.
Want the form?
The free change order form has the running contract math on it, comes as a fillable PDF, carries no branding so you can print it on your own letterhead, and ships with a second copy shown filled in for exactly the job above. No email required.
That one page covers Steps 2 to 7. Steps 1 and 8 need the two documents around it — the work authorization whose exclusions decide what counts as a change, and the Change Order Log that carries line B forward. Both are in the Trades Client Paperwork & Change-Order Template Pack, along with fourteen more, as fillable PDFs and editable Word files. If you want the definition rather than the procedure, start with what a change order is — or, if you are weighing this against a subscription, paperwork templates vs a contractor app. Every tool built for this stage sits on the templates for contractors hub.
