---
title: "Invoice numbers"
url: "https://support.wilson.menlo79.com/en/article/invoice-numbers"
language: "en"
last_updated: "2026-06-03T08:48:39.011Z"
---

# Invoice numbers

Invoice numbers are assigned when you finalize an invoice. Drafts stay without a final invoice number so that numbers are used only for completed, legally relevant invoices and the numbering logic stays clean.

The invoice note can be used for external references from a leading billing systems.

## Why use this change?

-   Less confusion: A draft clearly looks like a draft and not like an already valid invoice
-   Better traceability: The final invoice number is assigned only at the binding finalization step
-   Cleaner numbering logic: Pre-assigned numbers are avoided, so the sequence is easier to protect
-   Clear external references: Notes from other billing systems move into the invoice note instead of the invoice number itself

## How the change works

-   Invoice create page: The invoice number field shows the placeholder “n/a” while the invoice is a draft.
-   Draft invoice preview: The invoice number area also shows “n/a” instead of a number
-   Finalized invoice: After finalization, the assigned invoice number is visible in the preview

## How does the system behave?

-   Create draft → No final invoice number is assigned.
-   Edit draft → The invoice stays without a final number until it is finalized.
-   Finalize invoice → The system assigns and stores the next sequential invoice number.

💡 Note: This change applies only to newly created invoices. Older invoices stay untouched.

## FAQ

**Why does my draft not have an invoice number?**  
A draft is not yet a finalized, legally relevant invoice. That is why the number is assigned only on finalization.

**When is the invoice number generated?**  
The invoice number is generated exactly when the invoice is finalized and is then stored permanently.

**What happens to existing invoices?**  
Existing invoices stay unchanged. The new logic applies only to newly created invoices, so no migration is needed.

**Where should I store an external reference from another billing system now?**  
Use the invoice note for that. It replaces the previous workaround of manually overwriting the invoice number.