Almost every tradesperson knows the line: “While you're here, could you just do this as well?” “Just” turns into two hours and some materials. If it isn't written down anywhere, the final invoice often leads to arguments, and in the end you'd rather let the money go. A proper change order prevents that.
What is a change order?
A change order is an additional quote for a job that is already under way. You need one when something changes compared with the original quote:
- Additional work: the customer wants something that wasn't in the quote, for example an extra socket or an additional room.
- Changed work: the customer wants a different material or finish.
- The unexpected: the surface behind the tiles is rotten, or the pipe runs differently than expected.
Less work can also be a change order, just with a lower price.
The most important rule: confirm first, then work
The most common mistake is doing the extra work right away and discussing the price “later”. If there's a dispute, it's your word against theirs. This process works better:
- Describe the change briefly: what exactly needs doing and why?
- State the price: hours, materials, travel, equipment if needed. Same pricing basis as in the main quote.
- State the time impact: does the deadline move? That belongs in the change order too.
- Get it confirmed: ideally with a signature, or at least in writing by email or message.
- Only then do the work.
A verbal agreement isn't automatically invalid. But only what is written down can be proven later.
What goes into a change order?
- Reference to the main job: job number, site, date of the original quote
- A running change order number, for example “Change order 2”
- Description of the additional or changed work
- Reason for the change, such as “at the customer's request” or “substrate not load-bearing”
- Line items with quantity, unit and price
- Impact on the schedule
- A field for the customer's date and signature
- Photos showing the condition before the change, if needed
What the law says in Germany (briefly)
Under a construction contract under the German Civil Code (BGB), the customer can request changes (Section 650b BGB). You then make an offer for the additional or reduced payment. If you don't agree within 30 days, the customer can, under certain conditions, order the change in text form. Payment is then based on the costs actually required plus reasonable surcharges (Section 650c BGB).
If the VOB/B has been agreed, the rule is: for additional work, you must announce your claim to extra payment before you start the work (Section 2(6) VOB/B). If you forget, you risk losing the claim.
The details depend on the contract, and other countries have their own rules. For larger amounts or disputes, it is worth talking to your trade association or a lawyer.
Common mistakes that cost money
- Only agreed verbally and impossible to prove later.
- Change order only shows up on the final invoice, which surprises the customer and leads to arguments.
- Travel and small materials forgotten because the change was “only small”.
- No photo of the original condition. Especially with unexpected issues, that is your best evidence.
- Change orders not numbered. With several changes, you quickly lose track of what has already been confirmed.
Change orders in the final invoice
The final invoice should list all confirmed change orders with their numbers. Deduct any progress payments already made. That way the customer sees exactly how the final amount is made up, and there are fewer questions. In your job review, also check whether the change orders paid off for you. How to calculate with markups is explained in the guide Material markup in the trades.
Did the job pay off, change orders included? In Contractor Studio the job review compares plan and actual for revenue, materials, labour and travel and tells you in plain words what made the difference. You add change orders straight to the job and have them signed on your phone before work starts. The final invoice includes all confirmed change orders. Offline app, your data stays on your device, one-time purchase with no subscription.
Frequently asked questions
Does a change order have to be in writing?
Not necessarily, unless the contract says otherwise. But writing it down is strongly recommended so you can prove the work and the price later.
What if the customer won't sign the change order?
Then clarify whether they still want the extra work. Without an agreement, you shouldn't simply carry on. For construction contracts under German law, there are specific rules on the customer's right to order changes, see above.
Can I bill small extra jobs as a change order too?
Yes. All those small “we'll just do that quickly” jobs add up. A short change order with a price takes you two minutes.
How do I price a change order?
With the same rates as in the main quote: labour per hour, materials with markup, travel. That keeps the price easy for the customer to follow.
Change orders right on the job site
In Contractor Studio you create a change order directly on the job, with price, description and photos. The customer signs on the phone before you start. A check code later shows whether the confirmed change order has been altered. All confirmed change orders go into the final invoice automatically, and progress payments are deducted. The app runs offline with no subscription, and your data stays on your device.
This article is general guidance (as of October 2026) and is not legal advice. For specific disputes, contact your trade association or a lawyer.