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How much over an estimate can a contractor go?

California and New Jersey ask for written changes on home improvement jobs. Check your contract and your state.

What the paper says first

Your paper saysWhat to write
"Fixed price for the scope above"Add that a change of scope must be in writing.
"Estimate, may change if…" with named casesThis wording names when the price can move. Tell the customer before the cost occurs.
Only one number and no scopeAdd the scope and what the price covers.

This table is general guidance, not a legal rule.

Two state examples

  • California: a CSLB guide says that a change to the contract price must be a written change order that becomes part of the contract, signed by both sides.
  • New Jersey: N.J.A.C. 13:45A-16.2 requires a written contract for home improvement sales over $500, and all changes in its terms must also be in writing.

Check your state contractor board for any limit in your state.

How to go over without a dispute

  1. Stop before the added cost when you can.
  2. Show the customer the reason, with a photo.
  3. Write a change order with the added scope, price and days.
  4. Get a signature, then do the work.
  5. Add the change order as its own line on the next contractor invoice.

Wording that helps before the work starts

Sample wording, not legal advice: "This estimate covers the scope above. If we find hidden damage or you change the scope, we will send a written change order with the added price and days. We start that work after you sign it."

Also list what may move the price on your job, such as hidden pipe or rotten decking, and give a unit price for them where you can.

Write a contractor estimate

Short answers

Can a customer refuse to pay more than the estimate?

Ask a local lawyer. Use a signed change order for each added cost.

Sources and how this page was checked

Published by 731labs, the maker of InvoiceSnap. Last checked 11/09/2026. An AI tool helped draft this page. An automated check compared the legal facts and price ranges with their sources, using two AI models. No person reviewed this page. The sources are listed below. This page is general information. It is not tax or legal advice.