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Do you struggle with creating invoice numbers? If so, you're not alone. Crafting a properly formatted invoice that meets professional standards can be a complex and time-consuming process, especially if you lack prior experience. In this article, we'll examine several different invoice number formats and their variations, providing specific examples to help you find the one that best suits your needs.

Automation Using Prefixes

One of Numbero's core functions is to automate all invoicing-related processes. Although invoice numbers can be customized directly within the documents, Numbero recommends using the prefix function available in the company document settings. This feature automates the process of generating invoice numbers for future use.

We'll try to show you how it works in practice below. Please note that operating with prefixes and their combinations may seem a bit confusing at first, so we recommend keeping this article open while tweaking your company document settings.

Using Prefixes to Generate Unique Numbers

The prefix {N} stands for the document sequence number and is mandatory. You can indicate the desired reset period for the document sequence number, which can be a year, a month, or a day. To do this, you'll have to use an additional prefix. The combinations with extra prefixes work as follows:

  • We use the combination {NY} to reset the document sequence number to 1 at the start of a new year. The {Y} prefix is mandatory here.

  • We use the combination {NM} to reset the document sequence number to 1 at the start of a new month. Here, two prefixes - {Y} and {M} - are mandatory.

  • We use the combination {ND} to reset the document sequence number to 1 at the start of a new day. All {Y}, {M}, and {D} prefixes are mandatory here.

Example with {NM}

Using the prefix combination of INV-{NM}-{Y}-{M} will result in the invoice number being: INV-1-2023-3 in the “live” document.

You can also specify the minimum number of characters in the document sequence number by adding the number of leading zeros to the {N} prefix. In practice, this works as follows:

Example with {NM5}

Using INV-{NM5}-{Y}-{M} will result in the invoice number being INV-00001-2023-3.

As you can see, the only difference between this example and the previous one is in the invoice sequence number itself. Using {NM5}, we indicate that we want the invoice sequence number to include a minimum of five characters. 

Date Modifications Using Prefixes

Prefixes work the same way when we want to modify the dates. 

Here are some examples to illustrate how prefixes can be used to modify dates: 

  • {Y} - the year of document creation. You can indicate the minimum number of characters using {Y2}:

  • Example{Y} will be 2023, while {Y2} will be 23.

  • {M} - the month of document creation. You can indicate the minimum number of characters using {M2}:

  • Example{M} will be 3, while {M2} will be 03.

  • {D} - the day of document creation. You can indicate the minimum number of characters using {D2}:

  • Example{D} will be 9, while {D2} will be 09.

Example of a document sequence number with a modified date prefix: 


What you and your partners will see on the final invoice will look like this:

  • The first generated invoice in March will be INV00001-2023-03.

  • The second generated invoice in March will be INV00002-2023-03.

  • The first generated invoice in April will be INV00001-2023-04.

The Numbero team has created a highly customizable invoice number generator that produces document numbers based on the document creation date. For example, if the invoice creation date is 02/01/2023, the possible invoice number formats include:

  • PV-12-1/2023 - PV-{D}{M}-{N}/{Y}

  • PV-0102-1/2023 - PV-{D2}{M2}-{N}/{Y}

  • PV-0102-0001/2023 - PV-{D2}{M2}-{N4}/{Y}

Now, if we combine it with the document sequence number prefix that's reset every new month, we get:

PV-0102-1/2023 or PV-{D2}{M2}-{NM}/{Y}

In Conclusion

We recommend using the above information as an instruction manual when starting off with prefixes. While initially, prefixes and their variations may seem confusing, you will grow to understand how these formulas work once you start working with invoicing in practice.

If you still encounter any difficulties, feel free to contact us any time at Our specialists will help you overcome any problem quickly and easily.