What is a construction change order?

A change order is a written, signed document that modifies the original contract or proposal. It records a change to the scope of work, the price, and the schedule, and it must be approved before the extra work begins.

When should a contractor use a change order?

Use one any time the work differs from the signed contract: added or removed scope, hidden conditions found on site, owner-requested changes, or material substitutions. If it changes the price or schedule, it needs a change order.

What should a change order include?

A change order number, the original contract reference, the project and customer, a clear reason for the change, the change in work, the change in price (original total, this change, new total), the change in schedule, and signature lines for both parties.

Do both parties have to sign a change order?

Yes. A change order is only enforceable when both the contractor and the customer sign it, and it should be signed before the extra work is performed.

How to Write a Construction Change Order (+ Free Template)

A plain-English guide for contractors and estimators — any trade.

Few things cost contractors more money than doing extra work without getting it in writing. The job grows, you handle it to keep things moving, and when the invoice goes out the customer balks at the number. A change order is how you avoid that — and writing one takes about five minutes.

What is a change order?

A change order is a short, signed document that modifies your original contract or proposal. It records three things: what changed in the scope of work, what changed in the price, and what changed in the schedule. Once both parties sign, it becomes part of the contract.

When should you use one?

Any time the work differs from what you signed for:

You find a hidden condition on site (more area, rot, an obstruction the plans didn't show)
The owner or GC asks for something extra
A material gets substituted for a different price
The timeline shifts because of a change

Rule of thumb: if it changes the price or the schedule, it needs a change order.

What to include

Change order number and the original proposal/contract number
Project and customer details
Reason for the change — plain description of what changed and why
Change in work — what's being added or removed
Change in price — original total, this change (+/–), and the new total
Change in schedule — added days or a new completion date
Signature lines for both you and the customer

The one line that protects you: put in bold that "work will not begin until this change order is signed." Getting the signature before the extra work — not after — is the whole point.

Let AI write the first draft

The wording is the part people stall on. You can hand the facts to a chat AI (ChatGPT or Claude) and have it draft the "reason for change" and customer message in seconds. A prompt like:

"Write the 'reason for change' section of a construction change order. What happened: [we found 400 extra sq ft not shown on the plans that needs the same scope]. Added cost [$X]. Keep it clear and professional, and note that I need written approval before proceeding."

You still fill in the numbers and check it — AI is bad at math — but you start from a draft instead of a blank page.

Get the free change-order template + AI toolkit →

Do it automatically

If you'd rather not manage forms at all, Fieldscale generates and emails change orders for you and ties the added cost straight into job costing — so your profit number stays honest. And for the quantities behind the change, the free BuildTally calculators do the math.

Frequently asked questions

Does a change order have to be signed by both parties?

Yes. It's only enforceable when both the contractor and the customer sign — and it should be signed before the work is done.

Is a verbal change order valid?

Rarely worth the risk. Even a quick text or email confirming the scope and price beats a handshake you can't prove later. Get it in writing.

What if the customer refuses to sign?

Then you don't do the extra work. That's exactly what the change order protects you from — doing unpaid work you can't collect on.