Invoice numbering and number series

What it is for

Invoices are numbered sequentially within each calendar year. Without series, all invoices and delivery notes follow the Main numbering: it restarts from 1 every year and follows the form of the year’s last number (after 12/2026 it proposes 13/2026).

A number series is a separate sequence within the same year, for example 1/A and 1/B for two lines of business, or self-invoices in 1/AF. Each document belongs to the series its number indicates, even if it was typed by hand or imported.

Create a series

1. Open Settings → Payments and numbering and open the Number series section.
2. Tap New series.
3. Enter the Code (letters, digits, _ and -, up to 20 characters: it cannot be changed after saving) and the Description.
4. Under Documents choose Invoices, credit notes and self-invoices or Delivery notes.
5. Enter the Number format: {n} is the sequence number, {anno} the document year. For example {n}/A, PA{n} or {n}/{anno}/AF.
6. With Minimum digits the sequence number is padded with zeros: with 4 digits the first number of {n}/A becomes 0001/A. An example appears below the field.
7. If you like, open Document types that use it automatically and tick the types, for example self-invoices TD16-TD19.
8. Tap Save series.

Use it in documents

• On invoices, next to the number there is the Series field: type A, B or PA or pick one from the suggestions. A series already in use proposes the next number straight away; a new series starts from 1 (B-1) and is saved with the first invoice.
• On delivery notes, if you have delivery note series, a Series choice appears, with Main numbering among the options.
• If a series is linked to a document type, choosing that type makes Nanus propose a number from that series.
• The proposed number follows date, series and type until you type it by hand.

What Nanus checks

• The format must contain {n} exactly once and, if needed, {anno}; no other braces are allowed.
• The format must contain at least one letter, otherwise numbers get mixed up with the main numbering.
• The number cannot exceed the 20 characters allowed in an e-invoice.
• Two series for the same documents cannot produce the same numbers, and a document type can be assigned automatically to one series only.
• A number already used in the year blocks saving the invoice; a date earlier than the last invoice in the same numbering gives a warning, because numbers and dates must move forward together.

Edit or delete

Tap the description of a series in the list to change it. Description and document types can always be changed. Delete only works if the series has no documents yet; otherwise you see “The series already has documents and cannot be deleted.”

Once the series has documents, format, minimum digits and document kind can no longer be changed: they would move numbers already issued into another numbering. Decide the format before issuing.

See also

• Create an e-invoice
• Issue a self-invoice or integration (TD16-TD29)
• Issue a delivery note (DDT)
• Import data from other software
• Enter your company details