Last updated November 6, 2026
To convert a quote to an invoice, wait until the customer has accepted it, copy the agreed lines and prices into a new invoice, add the details only an invoice carries (its own number, an issue date and a due date), and send it. Invoicing software does the copying for you, so the two documents can't disagree.
The quote is an offer. The invoice is a request for payment and, in most countries, a tax document. Most of what follows comes from that difference.
What changes between a quote and an invoice?
The lines and prices carry over. Almost everything around them changes.
| Quote | Invoice | |
|---|---|---|
| Purpose | Offers a price | Asks for payment |
| Number | From the quote sequence | New number from the invoice sequence |
| Date that matters | Valid until | Due date |
| Customer details | A contact name can be enough | Full legal name and address, plus VAT number where required |
| Can it be changed? | Yes, until accepted | No. A sent invoice is corrected, never edited |
| Tax effect | None | Usually creates a VAT liability |
The customer details are the row people miss. A quote can go to "Maria at Bloom Studio". The invoice has to name the legal entity, and an accounts team will send it back if it doesn't.
When should you convert the quote?
Convert when the agreed billing moment arrives. That isn't always the moment the customer says yes.
- Small, quick jobs: invoice the full amount when the work is done.
- Larger jobs: invoice a deposit on acceptance and the balance on completion.
- Long projects: invoice at agreed stages. Our guide to progress billing covers how to set those up.
Whichever you use, write the stages on the quote itself. A deposit invoice is far easier to send when the customer has already seen "30% on acceptance" above their signature.
How to convert a quote to an invoice, step by step
- Confirm the acceptance. Keep the signed copy or the email saying yes.
- Check the quote is still valid. If it has expired, confirm the price before billing it.
- Copy the lines. Use your software's convert action rather than retyping.
- Complete the customer's details. Legal name, billing address, and VAT number if they have one.
- Add their reference. Ask whether they need a purchase order number on the invoice. Many larger customers can't pay without one.
- Set the dates. Use today's date for the issue date and the agreed payment terms for the due date.
- Check the tax rate. VAT generally follows the rate in force when the work is supplied, not when you quoted it, so a job quoted before a rate change may need the new rate.
- Issue and send. This is the step that gives the invoice its number and makes it final.
A worked example: one quote, two invoices
Here's an invented example. A renovation firm quotes €4,800 plus 20% VAT, with 30% due on acceptance and the balance on completion.
| Document | Net | VAT (20%) | Total |
|---|---|---|---|
| Quote QUO-2026-0042 | €4,800 | €960 | €5,760 |
| Invoice 1: deposit, 30% | €1,440 | €288 | €1,728 |
| Invoice 2: balance, 70% | €3,360 | €672 | €4,032 |
| Invoices together | €4,800 | €960 | €5,760 |
Check that last row every time. If the invoices don't add up to the quote, either a line was missed or the job changed and the paperwork doesn't show it yet. How VAT applies to the deposit varies by country, and the guide to deposit and final payment invoices goes through it.
What if the job changed after the quote was accepted?
Leave the accepted quote alone and add the change to the invoice as its own line. Label it so nobody has to ask, for example "Additional: rewiring in hallway, agreed by email 14 March".
If the change is large, send a short new quote for the extra work and convert that as well. It takes a few minutes, and it means the customer approved the extra cost before seeing it on a bill.
The mistakes that get invoices sent back
- A retyped price. One digit out and the customer's accounts team stops the payment.
- No purchase order number, when the customer needs one.
- The contact's name instead of the company's.
- An expired quote billed at the old price, when your costs or their scope have moved.
- Editing the quote after acceptance. Then you can no longer show what was agreed.
Converting a quote to an invoice in ERPFlow
In ERPFlow, open the quote, choose Convert to invoice, and the customer and lines are copied into a new draft invoice. The draft is dated today and falls due after the quote's payment term. The quote stays as it was, and the two documents are linked, so each one shows the other under Linked documents.
- To bill in stages, convert once for each stage. Every conversion makes a fresh draft of the whole quote, which you edit down to that stage's share before issuing.
- If the quote went to a lead, ERPFlow asks you to turn the lead into a customer first, then does the conversion in the same step.
- If you fulfil before you bill, convert the quote to an order and the order to an invoice. Orders are on the paid plans.
- When you issue the draft, it gets its number, such as
INV-2026-0042, and becomes final.
Customers can't accept a quote online or sign it electronically in ERPFlow. You mark the quote as accepted yourself, and can attach the signed copy to it.