Write up a change order when the customer says "while you're here..."

The job

Mid-job, the customer says "while you're here, can you also...". This 3-prompt chain turns your prices into a change order to sign before the extra work, writes the text to send with it, and updates it if they change their mind.

Who it's for

• HVAC, plumbing, roofing, remodeling and handyman owners who get add-on requests mid-job.
• Solo owners and small crews who write their own paperwork.

The prompt

Run all three in the same chat, in order. Start a new chat for each change order.

Prompt 1: the change order

I own a small home-service company. Draft a change order using only my numbers. Don't add, estimate or round any price.
Include:
- a reference to the original contract (number, date, amount)
- a plain-English description of each change, with its cost
- the total change amount and the new contract total
- what changes in the schedule, exactly as I state it
- a "Not included" section for anything I said is not part of this change
- approval lines for the customer and for me: printed name, signature, date
Don't give legal advice, add legal terms, warranties or promises I didn't give you. Plain text I can paste into my own form.

[PASTE JOB BLOCK]

Prompt 2: the text to send with it

Now write a short text (under 80 words) I can send the customer with this change order, asking them to review and sign before we do the extra work. Greet them naturally by the name in the job and sign off with my first name and business.

Prompt 3: when the customer changes their mind

The customer replied: "[PASTE STEP 3 CUSTOMER REPLY]". Update the full change order.

For [PASTE JOB BLOCK], give your business and first name, the customer, the original contract (number, date, amount, schedule), each change with your price, the schedule change, and anything not included. Prompt 3 is only for a changed request.

Worked example

Input (fake)

Business: Brightwater Plumbing (owner Dev, 555-0193)
Customer: Ms. Lindqvist, 220 Marrowstone Ave, Brightwater
Original contract: #P-0457, signed Oct 19, 2026. Repipe hall bath. Contract amount $3,480. 2-day job.
Changes:
- Replace 2 angle stop valves under the kitchen sink: $185 each.
- Replace the front hose bib: $210.
- Credit: customer is supplying her own bathroom faucet instead of the one in the contract: -$95.
No change to the schedule.
Maybe later: relocating the washer box. I'll price it after the wall is open. NOT in this change order.

Customer reply for Prompt 3: "Actually leave the hose bib, my brother-in-law will do it."

The traps: a credit to subtract, a maybe-item to leave unpriced, and a new total after the reply. Step 1 came to +$485, a $3,965 total.

Output

Claude · "Fable 5.1 High" · Pro · tested 2026-10-29 · run 1, job B. AI output from fake data, verbatim; passed C1-C7. Captured from page text; line breaks approximate.

Response 2 (the text)

Hi Ms. Lindqvist,

Attached is a change order for contract #P-0457 covering the two angle stop valves under the kitchen sink, the front hose bib, and the credit for the faucet you’re supplying. The change total is $485, bringing the contract to $3,965. No change to the schedule.

Please review and sign it before we start the extra work. Let me know if you have any questions.

Thanks,
Dev
Brightwater Plumbing

Response 3 (updated change order), excerpt. [...] marks each cut (business, customer, scope and customer signature lines).

CHANGE ORDER
[...]
Change Order No.: ________
Date: ________
[...]
ORIGINAL CONTRACT
Contract No.: P-0457
Signed: October 19, 2026
[...]
CHANGES TO THE WORK

Replace 2 angle stop valves under the kitchen sink
$185.00 each x 2 = $370.00
Credit: customer is supplying her own bathroom faucet instead of the one in the contract
-$95.00

Total change amount: $275.00
Original contract amount: $3,480.00
New contract total: $3,755.00

SCHEDULE
No change to the schedule.

NOT INCLUDED IN THIS CHANGE ORDER

Replacing the front hose bib. Customer’s brother-in-law will do this.
Relocating the washer box. This will be priced separately after the wall is open.

APPROVAL
[...]
Brightwater Plumbing
Printed name: Dev
Signature: ______________________________
Date: ________

What we liked: the credit is its own line, the totals are right, the washer box stays unpriced, and the number and date are left for you. The text quotes the old $3,965 total, so send the new one with the updated form.

Tool scores

A pass means usable as-is or after one small edit. Each 3-reply chain was judged on C1-C7 (see How we tested). Two runs on 3 fake jobs, so 6 chains per tool; Claude had one run, so 3.

ChatGPT doesn't show which model answers; tested on the High setting.

The main finding: every dollar figure in all 63 replies was right, before and after the customer changed their mind. The credit was always subtracted, and no tool priced a maybe-item.

The misses were in the wording: - An added clause. One Gemini change order added "By signing below, the owner/contractor and customer agree to the modifications described in this Change Order." - Dates and numbers you didn't give. Four chains filled in the test day's date; Gemini made up "Change Order #1" in three. - Couples' names. Every text to one couple opened "Hi Whitfields".

How we tested

• Date: 2026-10-29 (CT).
• Route: each tool's website, signed in, a new chat per chain.
• Tools, model labels and plans (as the apps showed them):
  • ChatGPT: Thinking effort: High. No plan label shown. ChatGPT doesn't show which model answers; tested on the High setting. The effort setting normally sits higher on our account; we tested on High.
  • Claude: "Fable 5.1 High", mode "Auto", plan Pro. One run per job (3 chats).
  • Copilot: "Auto", plan Personal.
  • Gemini: "Flash". Plan not shown.
• Runs: 3 fake jobs (HVAC, plumbing with a credit, roofing), 2 runs each; Claude 1 run.

A pass means usable as-is or after one small edit.

• Pass criteria. One small fix made a pass with a small edit; two or more made a fail.
  • C1: exact math in both change orders, credits subtracted.
  • C2: original contract number, date and amount referenced.
  • C3: schedule exactly as given, no invented dates.
  • C4: "Not included" items listed, not priced.
  • C5: approval lines for both sides (printed name, signature, date).
  • C6: no legal advice, added legal terms, warranties or promises.
  • C7: text of 80 words or less, greeting by name, signed by the owner, no [brackets].
• Checking: a script checked every dollar figure against the answer key; a person read every reply.
• Fake data only. All test data was made up. No real customers, jobs or prices were used.