Guide · Scope changes
Change orders, without the argument.
A change order is a written amendment to a signed agreement. It records what is changing — scope, price, schedule, or all three — and carries both parties' signatures before the changed work begins. This guide covers what a change order must include, the process that keeps you paid, how to price one fairly, and what to do when the client won't sign.
A Chalmsy guide · 10-minute read · Last reviewed 17 August 2026
What is a change order?
A change order is a formal amendment to the contract you already signed. The original agreement stays intact; the change order sits on top of it and records three things: what is being added, removed or altered, what that does to the price, and what it does to the schedule. Once both parties sign it, the change order carries the same weight as the agreement it amends.
That is the paperwork definition. The practical definition is blunter: a change order is the only thing standing between "sure, we can do that" and an unpaid invoice. Most scope changes don't arrive as formal requests. They arrive mid-walkthrough — the client points at a wall and asks whether it could go. You say yes, because it can, and because saying yes on site feels like good service. Then the job quietly absorbs the cost, the final bill surprises the client, and the argument starts over a conversation both of you remember differently.
The verbal yes on site is where margin dies. Not because clients are dishonest — because memory is soft and money is specific. A change order replaces two recollections with one document.
One boundary worth drawing: a change order amends a signed agreement. If nothing is signed yet, you are revising a proposal, which is a different document with different rules — the distinction is laid out in proposal vs estimate vs quote.
What should a change order include?
Five things, none optional. A change order that skips one of them invites the exact dispute it exists to prevent.
- A reference to the original agreement — the contract name or number, its date, and a sequential change order number (CO #3, not "the electrical thing"). The document has to say, unambiguously, what it amends. If your original proposal stated its exclusions clearly, this is where that discipline pays off: the change order can point at the exact exclusion the client is now buying. Writing that scope properly in the first place is covered in how to write a construction proposal.
- A description of the change — specific enough that a stranger could tell whether the work was done. "Additional electrical" is a fight waiting to happen; "add four recessed fixtures and one dimmer circuit in the dining room, per attached markup" is not.
- A cost breakdown — not just the total. Labor, materials and markup, itemized the way the original agreement was. A single unexplained number reads as a penalty; a breakdown reads as a price.
- Schedule impact — stated in days, even when the answer is zero. "No change to completion date" is a commitment worth having in writing; "adds six working days" is the sentence that ends the completion-date argument before it exists.
- Signatures from both parties, dated — before the changed work starts. An unsigned change order is a memo.
Many builders add one more line: a running total — original contract value plus all approved change orders to date. It costs you nothing and it means the client is never ambushed by the cumulative number at the end of the job.
How does the change order process work?
Five steps. The order matters more than the paperwork.
- Spot it. A change is anything outside the signed scope: a client request, a site condition nobody could see, a code requirement that surfaced at inspection. Train yourself — and your crew — to say "that's a change, let me price it" instead of "yes." The crew part matters. Most unpriced promises are made by whoever happens to be standing next to the client.
- Price it before you promise it. The temptation is to eyeball a number on site to keep the momentum. Resist it. A number said aloud becomes the ceiling: if the real cost comes in higher, you either eat the difference or open the negotiation from a position of having been "wrong." "I'll have a price to you by tomorrow morning" is a perfectly professional sentence.
- Put it in writing the same day you price it. Speed is half the system. A change order sent within a day of the conversation reads as process; one sent three weeks later reads as an invoice dispute in the making, and by then the client's memory of what they asked for has already drifted.
- Get the signature before the work. This is the step that fails most often, because the work is often faster than the paperwork. Hold the line anyway. The signature is what converts "extra work you chose to do" into "contract value the client owes."
- Invoice against the approved change. The change order should flow into your billing, not sit beside it. If you invoice in stages, the approved amount joins the relevant stage or gets its own line — either way, the invoice traces back to a signed document, not to a conversation.
Run this way, a change order takes minutes per change. Skipped, it takes one unpaid invoice to cost more than every change order you will ever write.
Should you fix the price or bill time and materials?
There are two fair ways to price a change. Which one applies depends on how well you can see the work.
Fixed price
When the change is fully visible — add a fixture, upgrade a finish, extend the deck two feet — price it fixed. The client knows the cost before they sign, and you carry the risk of your own estimate, which is fair because you can actually estimate it. Clients strongly prefer fixed numbers, and for known work you should give them one.
Time & materials
When the change is exploratory — open the wall and deal with what's behind it, chase the leak, remediate whatever the demo revealed — a fixed price forces you to pad against the unknown, and the client pays for risk that may never materialize. T&M is the honest structure here: agreed hourly rates, materials at cost plus a stated markup, and a not-to-exceed cap with an agreement to stop and reprice if you hit it. The cap is what makes T&M fair — it turns a blank check into a bounded one.
The unfair versions are the inversions. Fixed-pricing genuinely unknowable work means someone loses the coin flip — usually you. Billing T&M on work you could have scoped reads, correctly, as declining to commit. Pick the structure that matches the visibility, say why in the change order, and the pricing conversation mostly disappears.
How do you raise a change order without souring the relationship?
The discomfort is real. Mid-job, the relationship is warm, the client is standing next to you, and producing paperwork can feel like reaching for a lawyer. Three things make it feel like service instead.
Set the expectation at contract signing, not at the first change. One sentence when the original agreement is signed — "anything outside this scope gets a written change order with a price, before we do it" — means the first CO arrives as the process you promised, not a surprise escalation. The worst time to introduce the concept of a change order is the moment you need one.
Frame it as protecting both sides, because it does. The client gets the price before committing, in writing, with no end-of-job ambush. You get paid for the work. Say that plainly: "I write everything down so the final bill is exactly what you approved, line by line." Nobody hears that as adversarial. The paper trail is precisely what keeps the final bill from becoming a fight — and the clients who push back hardest on paperwork are, reliably, the ones you most need it for.
Keep the tone administrative. A change order is not an accusation and shouldn't read like one. Same template every time, same speed every time, whether the change came from them, from you, or from what was inside the wall. Consistency is what makes it feel like process rather than punishment.
This is not only a construction habit. Interior designers live the same problem on every furniture revision and every "while you're at it" — the trades change, the gap between the verbal yes and the signature doesn't.
What if the client stalls or refuses to sign?
Stalling first, because it is more common than refusal. A change order that sits unsigned for two weeks is usually not resistance — it is a client who doesn't grasp that the changed work is waiting on them. Put a validity window on the price ("good for 10 business days — material costs move"), and say clearly which work is paused pending signature. A deadline plus a visible consequence resolves most stalls without any tension at all.
Refusal splits into two honest cases. If the client doesn't want the change at the price quoted, that is a fine outcome — decline it politely and proceed under the original agreement, which is exactly what the original agreement is for. If the client wants the work but won't sign for it, you have learned something important early, at the cost of one awkward conversation instead of an unpaid invoice. Do not start the changed work. Work performed without an approved change order is work you have volunteered.
Two edge cases deserve real language in your original contract: concealed conditions (what happens when the wall is opened and the answer is bad) and a named person with authority to approve changes. Both clauses are cheap to include and expensive to lack — have your attorney look over the wording for your state. And if you are ever tempted to do the work first and chase the paper later: some contractors do recover through claims for the value of unapproved work, but that is a legal argument you fund after the fact, against a client who now has the leverage. The signature before the work is the entire point of the system.
Where the software comes in
How Chalmsy handles change orders
Chalmsy treats a change order as what it actually is — a new version of the signed agreement, not a tracking row in a project-management suite. The original proposal stays locked exactly as the client signed it. The change becomes version 2: drafted on top of the original, priced from your own rates, materials and multipliers (with hard-input prices the AI cannot alter), and sent for e-signature with email-code identity verification, valid under the federal ESIGN Act and state UETA laws. The client comments on the exact line they are questioning, on the document itself, photos included — so the negotiation happens where the record is, not across a week of texts. Once v2 is approved, the next stage invoice is raised from the approved version in one click, so what you bill is what was signed, by construction rather than by discipline.
To be clear about the boundaries: Chalmsy doesn't measure plans, hold a cost database, or estimate the change for you. You price the work; Chalmsy makes the writing, signing and invoicing side of it light enough that the paperwork actually happens the same day. See how the full flow works for building trades on the construction tour.
Asked and answered
The questions that come up.
What is a change order?
A change order is a written, signed amendment to an existing contract. It documents a change to the scope of work, the resulting change in price, and any impact on the schedule, and it is signed by both parties before the changed work is performed. Once signed, it carries the same contractual weight as the original agreement.
Can I do the work first and paper it later?
You can, and it is how most change order money is lost. Once the work is done, the client holds all the leverage: the price becomes a negotiation about a finished thing rather than a decision about a future one. Some contractors do recover for unapproved work through legal claims, but that is an expensive way to collect what a signature would have secured for free. Genuine emergencies aside, the signature comes before the work.
What should a change order include?
Five elements: a reference to the original agreement (contract number, date, and a sequential CO number), a specific description of the change, an itemized cost breakdown, the schedule impact stated in days, and dated signatures from both parties. A running total of the contract value including all approved changes is a worthwhile sixth. If any of the five is missing, you have a memo, not an amendment.
Does a change order need a signature to be valid?
Treat the signature as mandatory. Courts in some states have enforced changes agreed verbally or through conduct, but proving one turns into a dispute over two memories of a hallway conversation — the exact fight the document exists to avoid. Electronic signatures are legally valid under the federal ESIGN Act and state UETA laws, so there is no practical excuse for an unsigned change. For how your state and your contract's own change clause interact, ask your attorney.
What if the client refuses to sign a change order?
Then the change doesn't happen, and the job proceeds under the original agreement — that is a legitimate outcome, not a failure. If the client wants the work but refuses the paperwork, do not perform the changed work; work done without an approved change order is work you have effectively donated. Put a validity window on the quoted price and state which work is paused pending signature, which resolves most stalls on its own.
Who can approve a change order?
Whoever the contract says can. Your original agreement should name the person with authority to approve changes — on a residential job, typically every homeowner who signed; on a commercial job, a named representative rather than whoever is on site that day. Approval from someone without authority may not bind the client, so if the contract is silent, fix that before the first change arrives.
Stay calmsy
The next change, papered in minutes.
Start free and see what a change order looks like when it's a signed version of the agreement, not a spreadsheet row.