Quote to invoice in Belgium: deposits, milestones and conversion

Accepting a quote does not make VAT chargeable and does not oblige you to invoice. VAT becomes chargeable when you deliver the goods or complete the service, or earlier on any amount you collect in advance, and the invoice must follow by the 15th of the next month. A quoted project therefore often becomes several invoices (a deposit, one per milestone, a balance), all linked to the same quote, and none of them may bill the same amount or charge the same VAT twice.

This guide is for Belgian VAT-registered businesses that quote in OrdoGrid and then invoice the work. What each document means in law is in Invoice, credit note or quote, the content of a deposit invoice in Advance invoices in Belgium, and corrections after sending in Correct, cancel or credit an issued invoice.

When each invoice must be issued

Chargeable event

The event that makes VAT chargeable (fait générateur / belastbaar feit): delivery of the goods, or completion of the service or of an agreed stage. A payment collected before that makes VAT chargeable earlier on the amount paid. The invoice deadline runs from whichever comes first, not from the quote or the order.

What the law requires

• Deadline. The invoice must be issued at the latest on the 15th of the month after the chargeable event; for an advance, after the month you collect it; for services billed through successive statements or payments, after the period each one covers (Royal Decree no. 1, art. 4).
• Delivery or payment date. When it differs from the invoice date, the invoice states the date of delivery or completion (for a milestone, the sign-off date) or, for an advance, the payment date (art. 5 §1 5°).
• Earlier invoices. When several invoices cover the same transaction, each refers to the earlier ones and may not charge VAT that an earlier invoice already charged (art. 5 §1 11°).
• Format. Since 1 January 2026, when you are established in Belgium and the customer is a VAT-registered business also established in Belgium (since the Law of 10 February 2026 a Belgian VAT number alone is not enough), advance and stage invoices are structured e-invoices like any other, by default over Peppol (art. 53 §2bis of the VAT Code names advance payments). Quotes, payment requests and pro formas are not covered.
• A paid quote is not an invoice. If the customer pays against a quote or pro forma, VAT becomes chargeable on that amount and you must still issue the invoice.

What we recommend

• Ask for a deposit with a payment request and invoice it once paid, so the invoice date sits next to the chargeable event. If the customer will only pay against an invoice, agree the approach with your accountant.
• Whether a milestone is a stage of the service or an advance on the whole project depends on your contract. When unsure, invoice by the 15th of the month after whichever came first, sign-off or payment, and confirm with your accountant.
• Write the billing schedule (for example 30/40/30) in the quote, so each invoice traces back to an agreed stage.

Four ways to invoice a quote in OrdoGrid

Importer depuis un devis in a new invoice opens the same import window and links the quote too. Only quotes that are Envoyé or Accepté are offered.

How OrdoGrid tracks what is left:

• The Devis list (Reste under the amount), the import window and the Lier un devis picker show the amount still to invoice, VAT included, or Entièrement facturé (fully invoiced). It counts every linked invoice, drafts included, and does not deduct credit notes. Nothing stops you from invoicing more than the quote.
• The invoice PDF prints the quote number under Devis de référence (the label follows the document language: in English, "Reference quote"). On Peppol, the buyer reference is the purchase order number, else the payment communication, else the invoice number, so the rule requiring a buyer or order reference is always met (PEPPOL-EN16931-R003).

Step by step: from quote to sent invoice

1. Prepare the client and the quote

1. In Clients (page Base Clients), check N° de TVA and the address. If the customer uses purchase orders, tick Exiger un bon de commande pour les factures (Require a purchase order for invoices): OrdoGrid then asks for the number on every invoice. Quotes have no purchase-order field.
2. In Quotes (page Devis), click Nouveau devis. Put the core work in the base lines and add alternatives under Options du devis with Ajouter une option; ticked options count in the total and are invoiced. A proposal quote (Devis proposition) follows the same paths; it is numbered like 2026-LEMAIRE-001 when the client has a Slug devis.
3. Check Validité (30 days by default), write the billing schedule in Notes, then click Envoyer: quotes go by Email only, with a link to a response page.

2. Record the acceptance

• Online. The customer uploads the signed quote (PDF, PNG or JPG, 5 MB maximum) on a response page in French only; the quote becomes Accepté and keeps the file. This is an upload, not an electronic signature, and the customer cannot decline online. The page only accepts a quote that is Envoyé: for an expired, declined or already accepted quote it asks the customer to contact you.
• By email, letter or purchase order. Set Accepté with Statut and keep the evidence; set Refusé if the customer declines.
• Some options only. Before invoicing, open the quote with Modifier and tick exactly the options the customer signed.
• Validity passed. A sent quote turns Expiré automatically the day after its Validité date, and the customer can no longer accept it online. If the offer still stands, extend the Validité with Modifier (Edit): the quote returns to Envoyé. If the customer accepted through another channel, set it to Accepté under Statut.

3. Create and check the invoice

1. Whole quote: tick it and click Convertir en facture. If the client requires a purchase order, Bon de commande requis asks for it first.
2. In parts: click Facturer (first part) or + (next parts). In Articles à importer, tick the lines to bring over, click Importer n article(s), then set the description and amount of this part.
3. From a payment request: create the deposit request beforehand in Demandes de paiement with Nouvelle demande (it needs your company IBAN and goes by email, never on Peppol). Once it is paid, click Facture in its row, open the draft with Modifier and link the quote with Lier un devis before you send the invoice on Peppol or record a payment; after that, the quote link is locked with the amounts.

Before saving, check:

4. Save and send

1. Enregistrer commits the invoice number, even for a draft.
2. Click Envoyer, keep Envoi électronique via Peppol ticked for a Belgian VAT-registered customer found on the network, then Sauvegarder & Envoyer (Save & Send). The full routine is in Send your first Peppol invoice in OrdoGrid.
3. If the customer already paid, use Record payment in the invoice's Settlement panel.

Once an invoice is sent on Peppol or has a recorded payment, its amounts are locked; changes go through a credit note.

Worked example: a €10,000 project billed 30/40/30

Codex Lab SRL, a software studio in Liège, builds a customer portal for Transports Lemaire SA in Charleroi. Both are Belgian VAT-registered and Transports Lemaire receives on Peppol and uses purchase orders. The quote bills 30% on signature, 40% when the test version is approved and 30% at go-live. Codex Lab's document language is French, so the line texts and notes below are in French.

Only the four invoices count for VAT; the quotes and the payment request do not.

1. 12 May. Quote D-2026-0058: base line "Portail client – analyse, développement et mise en production", €10,000.00 at 21%, plus an unticked option "Module de paiement en ligne", €1,500.00. Validité: 11 June.
2. 20 May. The customer uploads the signed quote without the option: Accepté. Purchase order 4500012345 arrives by email, so Codex Lab ticks Exiger un bon de commande pour les factures on the client. No VAT is chargeable yet.
3. 21 May. Payment request DP-2026-0019, "Acompte 30 % – devis D-2026-0058": €3,000.00 + €630.00 VAT = €3,630.00.
4. 27 May. €3,630.00 arrives. VAT on €3,000.00 is chargeable in May: the invoice must be issued by 15 June.
5. 28 May. Facture on the request, purchase order entered: draft F-2026-0071. Codex Lab changes Date from 21/05/2026 to 28/05/2026, adds "Acompte reçu le 27/05/2026" in Notes and links D-2026-0058 under Devis lié. Once the invoice is saved, the Devis list shows Reste €8,470.00 for the quote. It sends on Peppol and records €3,630.00 with Record payment.
6. 8 and 10 July. The test version is approved on 8 July, so this invoice must be issued by 15 August. On 10 July, the + icon imports the base line, renamed "Jalon 2 (40 %) – version de test validée le 08/07/2026 – devis D-2026-0058" at €4,000.00: F-2026-0098, €4,840.00. €3,630.00 is left.
7. 5 August. The customer wants a CSV export for its accountant. Instead of editing the signed quote, Codex Lab has a second quote D-2026-0074 accepted: €800.00 + €168.00.
8. 16 September. Go-live, with the CSV export, was on 15 September, so both remaining invoices must be issued by 15 October. With + on D-2026-0058, Codex Lab creates F-2026-0120 for €3,000.00 + €630.00, noting "Solde (30 %) du devis D-2026-0058 – mise en production le 15/09/2026. Factures antérieures : F-2026-0071 (acompte) et F-2026-0098 (jalon 2)." In the Devis list the quote now shows Reste €0.00, and the import window lists it under Entièrement facturé. It then converts D-2026-0074 with Convertir en facture and adds "Export CSV livré le 15/09/2026" in Notes: F-2026-0121, €968.00, and D-2026-0074 shows Converti. With the proposed Communication kept, F-2026-0120 carries +++002/0260/12021+++.

The final invoice charges VAT only on the €3,000.00 balance; the €630.00 and €840.00 invoiced earlier are referred to, not charged again. Convertir en facture on D-2026-0058 that day would have been refused: three invoices are already linked to the quote.

Edge cases and common mistakes

If an in-scope customer cannot technically receive on Peppol, you still issue the invoice, as a PDF: see Belgian B2B e-invoicing obligation 2026. Purchase order practice is in PO number on a Belgian invoice.

Evidence to keep

• The quote and its acceptance: the signed file (kept with the quote in OrdoGrid) or the acceptance email, plus every revised or additional quote and the purchase order.
• The sign-off of each milestone and the bank statement line of each advance: they date the chargeable events.
• Every invoice, as PDF and, for Peppol, the XML from Peppol → Outbox, for 7 years from 1 January of the year after issue (art. 60 of the VAT Code, as amended by the Law of 18 December 2025). We recommend keeping the quote file for the same period.

Select rows in Factures or Devis and click Download (tooltip: Download as ZIP) for your accountant. OrdoGrid is not a legal archiving service and gives no retention guarantee.

FAQ

Does a signed quote make VAT chargeable?

No. Signing creates the commercial agreement, not a chargeable event. VAT becomes chargeable when you deliver, complete an agreed stage or collect a payment, and the invoice follows by the 15th of the next month.

Should I invoice the deposit before or after it is paid?

The legal trigger is the payment: VAT becomes chargeable on the amount collected and the invoice must be issued by the 15th of the following month. We recommend a payment request first and the invoice once paid; if your customer insists on an invoice first, agree the approach with your accountant.

Can the quote number become the invoice number?

No. Quotes and invoices have separate series in OrdoGrid (D- and F- by default), and the invoice takes the next invoice number. The quote number is printed on the invoice under Devis de référence.

How do I deduct the deposit on the final invoice?

Invoice only the remaining amount and refer to the earlier invoices by number in Notes. The final invoice may not charge VAT that was already invoiced, and OrdoGrid does not accept negative invoice lines.

The customer accepted only some options. What do I invoice?

Only what was accepted. Tick the accepted options on the quote before converting, or untick the other lines in the import window when you use Facturer.

The quote expired but the customer still wants the work. What now?

If the prices and VAT rates still hold, extend the validity date with Modifier: the quote returns to Envoyé and the customer can accept it online. If the customer already accepted in writing, set the quote to Accepté under Statut. Otherwise duplicate it, update the prices and send the new quote for acceptance.

Can I convert a quote twice by mistake?

Convertir en facture refuses a second full conversion, and the conversion of a quote that already has a linked invoice. Facturer and the + icon do not stop you, so check the Facture column and the remaining amount before saving.

Can I send a quote over Peppol?

No. The Belgian obligation covers invoices and the credit notes that correct them, and OrdoGrid offers Peppol only for those. Email the quote.