Convert an accepted estimate into an invoice

convert_estimate_to_invoice copies the accepted quote into a draft invoice and links the two. It refuses declined and expired quotes, returns the existing invoice when the quote was already converted, and notes when a quote was converted without formal acceptance.

Written and reviewed by the Billr team. Published 2026-09-20, last reviewed 2026-09-20.

Who this is for: Anyone who quotes work and starts it once the client agrees.
Billr capabilities used: convert_estimate_to_invoiceget_estimateget_invoice

What you need first

An estimate that has been sent and answered, ideally with status accepted.
A key with the Read and draft profile.
The estimate id, from list_estimates or get_estimate.

Step by step

01Check the estimate status
get_estimate returns the status and the converted invoice id when there is one. Converting an already-converted quote is safe but pointless, and the server says so.
Example
```
get_estimate  {
  "estimate_id": "a4f1c8d2-6b39-4e07-9d51-2c8a6f3b1e94"
}
```
02Convert it
Only the estimate id is required. issue_date and due_date are optional overrides for the new draft, which otherwise takes today and the business payment terms.
Example
```
convert_estimate_to_invoice  {
  "estimate_id": "a4f1c8d2-6b39-4e07-9d51-2c8a6f3b1e94"
}
```
03Read the result carefully
The summary names the new invoice number and total, and mentions when the estimate was not formally accepted. already_converted: true means nothing new was created and the existing invoice came back.
04Send it when you are ready
The new invoice is a draft like any other, so it is reviewed, corrected and then sent with send_invoice under a key that has the send scope.

Worked example

Fictional account, field names as returned by the server

You say

Harbor & Lane accepted EST-0213, turn it into an invoice.

Your agent calls

convert_estimate_to_invoice { "estimate_id": "a4f1c8d2-6b39-4e07-9d51-2c8a6f3b1e94" }

Expected response, abridged

{
  "summary": "Converted estimate EST-0213 into draft invoice INV-1151: $4,100.00. Call send_invoice to deliver it.",
  "already_converted": false,
  "invoice": {
    "invoice_number": "INV-1151",
    "status": "draft",
    "total": 4100
  }
}

Limits and gotchas

Declined and expired quotes cannot be converted; create a fresh estimate instead.
The estimate becomes converted and can no longer be edited or sent.
Converting does not send anything. Delivery is a separate, scope-checked call.
The invoice takes the estimate lines as written; it does not attach logged time or expenses.

Troubleshooting

"Estimate EST-0213 is 'declined'": The client declined this quote. Reissue the scope as a new estimate and get an acceptance before invoicing.
The summary warns the estimate was not formally accepted: The quote was still sent or viewed. Convert only when you have the client agreement you rely on; the note exists so the record is honest.
Two invoices exist for one quote: Only one invoice can be linked, and retries return it rather than creating another. Check the estimate for converted_invoice_id before assuming a duplicate.

Sources

Reviewed 2026-09-20 against Billr's own tool implementations and the client documentation linked above.