Hi,

Invoices are based on the account.move model (with type = 'out_invoice' for customer invoices).

Their numbering is controlled by the journal’s sequence, not the sales order or a global setting.

Steps to Customize Invoice Sequence

1- Enable Developer Mode

               * Go to Settings → Activate Developer Mode

2- Go to Accounting → Configuration → Journals

              * Open the Sales Journal (usually named “Customer Invoices”)

3- Check the “Sequence” field

             * Scroll to Advanced Settings

             * Click the linked sequence under “Next Number” or “Sequence”

4- Edit the Sequence Settings

             * Change the Prefix (e.g. INV/%(year)s/)

             * Change Padding (e.g. 5 digits → 00001)

              * Modify Next Number

5- Save and test by creating a new invoice.

Eg:

If you want invoice numbers like:

FAC/2025/00001

Set the sequence:

    Prefix: FAC/%(year)s/

    Padding: 5

    Next Number: 1

For more information:-

- https://www.youtube.com/watch?v=4DovbBdVkjI

- https://www.odoo.com/documentation/18.0/applications/finance/accounting/customer_invoices/sequence.html

- https://www.odoo.com/sl_SI/forum/pomoc-1/changing-invoice-number-sequence-in-odoo-16-214660

Hope it helps

Hi LaurentC,

Please try this Module: https://apps.odoo.com/apps/modules/18.0/account_move_name_sequence