Invoice Numbering Rules You Must Follow to Stay Compliant
Invoice numbering is based on a continuous chronological sequence. Invoices must be issued "in order." It is not possible to skip an invoice
Choosing the micro-enterprise regime simplifies your accounting. Regardless of your legal status, one universal rule applies: you must number your invoices. An accountant can assist with this. If not, we provide all the guidance you need to number your invoices like a professional.
Numbers must be unique
Invoices are unique accounting documents.
- As such, their number must be unique.
- Multiple invoices cannot have the same number.
Note: It is forbidden to delete an invoice. You can cancel it and replace it (with a new number), but the first version must still appear in your accounting. If the invoice has already been paid, you must issue a credit note.
The numbers must be consecutive.
Invoice numbering is based on a continuous chronological sequence. Invoices must be issued “in order.” It is not possible to skip an invoice number. It is also not permitted to issue an invoice retrospectively and slip its number between two existing numbers. In any case, the invoice must always be produced and transmitted at the time of the sale, not afterward.
The invoice number must appear on all pages and be followed by a pagination sequence such as: page number/total number of pages.
Examples of invoice numbering
There is no rule for the format of invoice numbers, as long as they are consecutive and continuous. A simple consecutive order can be used: 001, 002, 003, 004, and so on.
You don’t have to start numbering at 1.
The first invoice number can be any, as long as the following ones are continuous and chronological.
Invoice numbering with a time prefix
It is common to include a date in invoice numbering to facilitate filing. To do this, you can follow the year-number or year-month-number model. Thus, your invoice numbers will be of the type “2026-130” or “2026-05-130”. You can reset the numbering to zero at the beginning of each period, but this is not recommended, in order to maintain numbering continuity.
Invoice numbering with another prefix
It is possible to use several different numbering series:
- if you have separate activities;
- if you have multiple billing sites;
- if you have multiple customer categories with different billing rules;
- if you use multiple invoicing systems.
In this case, it is best to use different prefixes to ensure that two invoices with the same number cannot be produced. The invoice numbers in each series must remain chronological and continuous in all cases.
Numbering your invoices like a pro: in brief!
To avoid any risks in the event of an inspection and to correctly number your invoices, here are the main rules to follow:
- numbers must be unique;
- the numbers must follow each other;
- there can be no jump in the numbering;
- the invoice number must appear on all pages;
- an invoice number cannot be assigned retrospectively ;
- Once an invoice is created, it cannot be deleted or its number reused.
To avoid any errors, when you issue an invoice with Billed, the system automatically suggests the number following that of the previous invoice.
Frequently Asked Questions
Is it possible to change the numbering format of my invoices?
Yes, you can change the numbering type of your invoices (simple sequence, time prefix, other prefix, etc.). You can do this at any time. However, it is recommended to wait until the start of a new fiscal year to ensure consistent numbering.
How to number credit notes?
Credit notes can be processed like any other. The numbering rules are the same, and these invoices are included among the other invoices. However, you can choose to include them in a separate series and differentiate them from regular invoices. Each series must have a distinct prefix.
What happens if an invoice number is wrong?
If an incorrect invoice is sent, the business must issue a cancellation invoice with a new invoice number. This invoice should include a negative amount, the original invoice number, and the issue date. Afterward, a correct invoice can be issued with a different number.
Does an invoice number matter?
Numbering invoices is beneficial for any type of invoice. Invoice numbers are crucial for business recordkeeping. For freelancers or business owners, they assist with accounting and payment tracking. This is particularly useful when issuing multiple invoices each month.