Does this invoice match the quote?

The move Before you question an invoice, sort every line against the quote and every change approved in writing since. Then ask the vendor only about the lines with no approval or no way to check.

Marco's invoice for the Brightwater Dental pages came in at $5,760, against a $3,900 quote. You're about to email him about the $1,860.

On October 2, OpenAI published a case study about Chatham, a capital-markets advisor that built a tool to check each trade record against what the client authorized.

Run that check on Marco's bill. You authorized more than the quote: $600 of the $1,860 is the Careers page you approved by email on September 15. Ask Marco about that, and he'll forward your own email back.

The quote is where the agreement started. Check the bill against where it ended up. Sorted that way, Marco's bill looks like this (he and his invoice are made up for this example):

Matches the quote: $3,900
- Five pages at $780 each

Approved later in writing: $600
- Careers page. Your Sept 15 email: "Yes, go ahead and add the Careers page at $600."

Can't check from what you pasted: $180
- Stock photos, billed "per the licensing schedule in Attachment B." Attachment B isn't in the paste.

No approval found: $1,080
- FAQ page, $600. No request or price in the thread.
- Revision round 3, $480. Marco's Sept 18 email said "unless you say otherwise." No reply in the thread.

Total: $5,760

Why this helps: $4,500 of the bill now has a paper trail, and Marco gets three questions about the other $1,260 instead of one big number to defend.

The move: fill in the four lines at the bottom of this prompt.

I need to decide whether to pay an invoice as billed or ask the vendor about parts of it first. Sort the bill before you draft anything.

1. Put each invoice line in exactly one group, with a subtotal for each group:
- Matches the quote
- Approved later in writing (quote the approving sentence word for word, with who wrote it and the date)
- Can't check from what I pasted (name what's missing)
- No approval found
Confirm the subtotals add up to the invoice total. A vendor's "unless you say otherwise" with no reply is not an approval. If two documents set different terms for the same work, show both and ask me which applies.
2. List what I should check in my own records first, such as a reply, call or text I didn't paste.
3. Draft a short, friendly note to the vendor about the last two groups only. For each line, ask for the one thing that would settle it: a log of the hours for hourly work, the missing document for a "Can't check" line, and otherwise who asked for the work and where the price was agreed. Don't ask the vendor to confirm my own replies or approvals. Leave out compliments, payment promises, requests to drop a charge and claims about my records.

Don't tell me what to pay. That's my decision. If the quote or the invoice is missing, ask me for it before you start. A missing attachment goes under "Can't check."

My situation: [who the vendor is, what the work covered, who else is affected, and what you want]
Quote: [paste]
Later emails: [paste, or write "none"]
Invoice: [paste]

Try it first with Marco's paperwork:

My situation: I'm a solo marketing consultant. I subcontracted Marco Reyes, a freelance web writer, to build pages for my client, Brightwater Dental. Brightwater pays me and I pay Marco. I want to pay what we agreed, keep working well with Marco, and avoid surprising Brightwater with extra costs.

Quote (from Marco Reyes, accepted by me by email on September 3, 2026):
- Five pages (Home, About, Services, Team, Contact): $780 per page, $3,900
- Each page includes two revision rounds. Additional rounds: $80 per hour
- Additional pages quoted separately on request
- Stock photos: billed at cost per the licensing schedule in Attachment B

Later emails:
September 15, 2026, me to Marco: "Yes, go ahead and add the Careers page at $600."
September 18, 2026, Marco to me: "Brightwater sent a new brand guide, so all five pages need another revision pass. I'll start Monday at $80/hour unless you say otherwise."
September 24, 2026, Marco to me: "Headings are updated on all pages. I also saw FAQ text in Brightwater's shared doc, so I built it out as its own page."

Invoice:
Invoice #1047 from Marco Reyes, dated October 6, 2026
1. Website pages per quote (5 x $780): $3,900
2. Careers page: $600
3. FAQ page: $600
4. Revision round 3, heading updates (6 hours x $80): $480
5. Stock photo licenses (4 images): $180
Total due: $5,760

What stays yours: what you owe. The sort sees only what you paste, so find each quoted approval in your own inbox and cut any line from the note you can't confirm.

Paste vendor paperwork only into an AI tool you're allowed to use. ThinkShift tested this prompt and sample as plain text sent to Claude Opus 5.5 from a script, not in the Claude app or other AI tools.

What to skip this week: shopping for invoice-checking software. Chatham built its own tool. Your invoice needs only the same check, run on pasted text.

A bill that doesn't match the quote can still match the agreement.

Go deeper

The October 2 case study on Chatham's record-versus-authorization checks