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How to write a change order for a home service project

Scope changes mid-project are fine. Doing the extra work before the client signs isn't. Here's how to write a change order that protects you and moves fast.

By Homefront Pro·6 min read·Updated August 3, 2026

The homeowner is standing next to you in the kitchen. You're there to replace the countertop. She points at the backsplash tile and says, 'While you're here, can you just replace a few of those too?' You say sure, no problem. Two days later you hand her the invoice. She's surprised by the extra $600. 'I didn't think it would be that much,' she says. 'We didn't discuss a price.' Now you're in a conversation nobody wins. She thinks she's being overcharged. You think you're being stiffed for work you did. You're both right, because nothing was agreed in writing.

Verbal agreements on extra work are where margins disappear. Not because clients are dishonest, but because people hear what they wanted to hear. The client heard 'sure, no problem' and didn't think about cost. You thought the price was clear given what materials and labor run. Three weeks later when the invoice arrives, you have two different memories of the same conversation and no document to settle it. A scope dispute with no paper behind it is a coin flip. Sometimes you win. Sometimes you eat the cost.

A change order breaks that cycle. It documents the extra work in writing, puts a price on it, and gets the client's signature before a nail gets pulled. The client knows what they're approving. You know you're covered. Here's how to write one.

The sequence matters: agree on scope and price, get the signature, then start the work. Not the other way around.

California requires covered home improvement contract changes to be in writing and signed before the changed work starts.

California Business and Professions Code § 7159

Step by step

  1. 1

    Recognize scope creep the moment it starts

    When a client says 'while you're here, can you also...' that's where a change order becomes necessary. The original estimate didn't include that work. Before you say yes to anything outside the original scope, pause and size the ask. A cracked outlet cover is a 10-minute favor. A bathroom floor isn't. The rule: if it wasn't on the original estimate, it doesn't get done without written approval. You can still say yes to the extra work. Just say it with paper. Something like: 'Sure, I can do that. Let me put together a change order so we're both on the same page before I start.'

  2. 2

    Price the extra work before you write a number

    Don't price off the top of your head. Walk the scope before you put a number on it. Check material quantities, pull prices from your supplier list, and price the labor at your standard rate. Then add your markup. If there's any uncertainty (what's behind the drywall, whether the subfloor is solid), build in a buffer. A change order that goes over its price after the client signs causes more friction than the scope creep it was meant to fix. If you can't see the full scope yet, write a time-and-materials change order for the discovery work and a fixed-price one after you know what you're dealing with.

  3. 3

    Write the change order with the right fields

    Keep it short and specific. The client shouldn't need to read it twice to know what they're approving. You need: a plain-language description of the extra work, line items with quantities and unit prices, the revised project total, and payment terms for the added amount. Include the date and reference the original estimate number. Label it 'Change Order' at the top, not 'Revised Estimate.' A revised estimate implies the original agreement is changing. A change order says it's an addition. That distinction matters if a dispute comes up, because both documents stay on record and you want the original approval intact.

  4. 4

    Set an expiration date

    A change order without a deadline is an open invitation to drag things out. Set an expiration of 3 to 5 business days from the date you send it. That gives the client time to review without giving them a week to get a second opinion on work you're already standing next to. An expiration also creates a natural check-in point: 'Did you get a chance to look at the change order I sent?' is an easier call to make when you've already told them it expires Friday. If they let it expire, write a fresh one. Material prices shift. Your schedule does too.

  5. 5

    Send it through the client portal and wait for the signature

    Send the change order before you start the extra work. Agree on scope and price first, get written approval, then do the work. If you use Homefront, send a new estimate with the added scope and have the client sign that record before starting.

  6. 6

    Hold the line: no signature, no work

    Some clients push back. They may say the price is too high, they thought it was included, or they will sign later. Pull up the original estimate, walk through the added line items, and wait for written approval before starting the extra work. Clear terms protect both sides.

  7. 7

    Tie the change order to the final invoice

    When the project is done, the final invoice should reflect the original scope and every approved addition. Keep the original estimate, each signed change order, and the final invoice together. If you use Homefront, create the invoice from the approved estimate and review the added scope before sending; the app does not currently create or roll up change orders for you.

Common questions

Does a change order need to be in writing by law?

It depends on the state, contract, project, and change. California requires covered home improvement contract changes to be in writing and signed before the changed work starts. Other states have different rules. Even when the law does not spell it out, written approval reduces disputes. Ask counsel about your location and contract.

What's the difference between a change order and a new estimate?

A change order amends an existing signed agreement by adding or removing scope and cost. A new estimate starts a separate document. Whichever record you use, identify the original scope, the added work, the price, and the approval date, then keep the documents together.

What if the client says they'll sign it later?

Don't start the extra work. 'Later' becomes 'I forgot' or 'I never agreed to that.' The change order creates a record at the moment of decision, not the moment of billing. If you start the work and invoice for it after the fact, you've given up the protection the change order was meant to provide. Send the change order, wait for the signature, then pick up the tools.

Can a client dispute a change order they already signed?

They can still dispute it. A signed record gives both sides a clearer document to review, including the scope, price, and signing event. It helps, but it does not guarantee the outcome of a dispute.

How do change orders affect the final invoice?

The final invoice should reflect the original estimate total plus approved changes. Reconcile each added line before sending and show the client how the total changed. Do not assume your software will combine separate documents automatically.

What if the extra work costs more than the change order price?

For a fixed-price change order, the signed price is the number the client approved. If the scope is still unknown, write a discovery or time-and-materials agreement with clear limits, then get approval for the fixed-price work once you know the conditions.

Related

  • E-signatures
  • Client portal
  • Online payments
  • Built for general pros
  • Built for remodelers

Sources

  • California Business and Professions Code § 7159
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