# Source: https://getlago.com/docs/guide/invoicing/invoicing-settings/invoice-numbering.md

> ## Documentation Index
> Fetch the complete documentation index at: https://getlago.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Invoice numbering

> Define how invoice numbers are generated — per customer or across the billing entity.

## Invoice numbering[](#invoice-numbering "Direct link to heading")

With Lago, invoice numbers are automatically generated each time an invoice is finalized. You can configure how these numbers increment to match your billing entity structure and customer management needs.

* **Per customer**:
  Generates a unique invoice sequence for each customer.
  This method ensures isolated and traceable numbering per customer, which can simplify customer-level reporting and accounting.
* **Entity-wide numbering**:
  Uses a single, continuous sequence across all customers within a billing entity.
  This option streamlines invoice tracking at the entity level. The numbering increments monthly, using a YYYYMM pattern to help segment invoices by period.

## Invoice prefix customization[](#invoice-prefix-customization "Direct link to heading")

Lago also allows full control over the prefix applied to documents like invoices and credit notes.
By default, the prefix combines:

* The first three letters of your billing entity’s name, and
* The last four digits of your entity ID.

You can override this with a custom prefix to better reflect your internal conventions or branding needs.
This helps maintain consistency, clarity, and professionalism across your documents.