Ever finished a home project, paid the final bill, and breathed that sigh of relief—only to get a surprise message from your contractor saying you owe even more? It happens more often than most homeowners realize. If a contractor wants to charge more after the work is done and paid for, it can leave you feeling frustrated and unsure of your next move.

Let’s break down your rights, why this happens, and exactly how to respond if you get hit with an unexpected invoice.

Why Would a Contractor Send an Extra Invoice?

Usually, when you sign a contract and pay the agreed price—especially after the job’s complete—everyone expects that’s the end of it. But sometimes, a contractor might realize they underestimated materials or labor costs. In this case, the story started when the homeowner specifically asked for pressure treated lumber for their deck repair. The crew showed up with regular lumber instead. Once the mix-up was fixed (thanks to clear communication from the homeowner), the job was finished, the balance was paid—and then a week later, an extra invoice was threatened for “upgrading” the lumber.

So why does this happen?

• Miscommunication: The contractor may claim they misunderstood the scope or materials.
• Unanticipated Costs: Sometimes contractors forget or overlook certain expenses during estimation.
• Poor Documentation: If job details aren’t written clearly in the contract, confusion can arise later on.
• Owner Approval: Sometimes materials or upgrades are changed on the fly—but unless you agreed in writing to pay more, this shouldn’t be your responsibility.

The good news is, in most cases like this one, you have strong protections on your side.

Your Rights When a Contractor Wants to Charge More

Consumer protection laws exist in many states to help homeowners avoid paying unfair or unexpected charges. If your contract spells out exactly what work will be done for an agreed price—and you pay that price—contractors generally can’t tack on new charges afterward without your written approval.

A few key points:

• If you didn’t sign a change order or agree in writing to any price increase before the work was done, you typically aren’t obligated to pay extra.
• Many states require “change orders” (written agreements for extra work or materials) for any cost increase above the original estimate. Learn more from the Federal Trade Commission’s guide on hiring contractors.
• If the contractor made a mistake (like forgetting you wanted pressure treated lumber), that’s not usually grounds for billing you later.
• Once you’ve paid in full according to the signed contract and invoice, most contractors can’t legally demand more unless there was fraud or major misrepresentation.

In short: unless you approved new costs in advance (ideally in writing), you’re likely on solid ground refusing extra charges.

How Should You Respond?

If a contractor wants to charge more after the work is done and paid—as in this pressure treated lumber situation—the best approach is calm but firm communication. Here’s a simple way to reply:

• Politely remind them of the original agreement and payment.
• Point out that no change order or extra charge was discussed or signed before work was completed.
• State that you consider the contract fulfilled and are not responsible for additional charges.
• If they persist, ask for documentation showing your agreement to extra costs.
• If they threaten collections or legal action, consider contacting your state’s consumer protection agency or a local attorney (many offer free consultations for these situations).

For a sample response letter and more guidance on handling disputes like this, check out this helpful resource from Nolo on contractor overcharges.

Lessons Learned — A Real-Life Anecdote

Stories like these aren’t rare. One homeowner described finishing a kitchen remodel only to get a surprise bill three weeks later for “extra time” spent on tile installation. There was no mention of extra costs during the project—and nothing in writing. The homeowner stood their ground, pointing to the original contract and receipts. The contractor eventually backed down, admitting the mistake.

Clear communication (and written documentation) saved the day. When both sides stick to what’s agreed on paper, surprises like these are much less likely.

What Would You Do?

If you were in this situation—paying for a deck repair exactly as agreed, then getting an unexpected invoice for “upgrades”—how would you respond? Have you ever faced a surprise bill from a contractor?

Share your story or advice below. The more homeowners know about their rights when a contractor wants to charge more after the work is done, the less likely they are to fall for unfair billing.