To change the system-generated document number, the user can modify the document number field. However, please keep in mind that the new document number is generated according to the setup under Settings > Sales and finance > General.
When selecting By last number, the system will add 1 to the number of the document that was created last.
By largest number will trigger the system to find the largest existing document number (which may not be the last, since the numbers can be edited) and add 1 to create the new sequence number.
The setting of using the largest invoice number +1 is activated.
If you wish to start numbering invoices from 2001, type it in. The next invoice created will be 2002.
To change the numbering of invoices at the beginning of a new year, create a new document and type in the number you'd like to start the year with. E.g. at the beginning of 2021 the number could be 2101. The next invoice created will have the number 2102 and so on.
There's also a possibility to add a project number in front of the quote number. You can activate the feature under Settings > Sales and finance > Quotes.If you wish to display the invoice issuer ID in front of the invoice number, tick this option under Settings > Sales and finance > Invoices.
Then go to Settings > Administration > Users and groups, click on the name of the user, and set up an invoice issuer ID number.
If you are using multiple entities, each entity has its own automatic document numbering since documents aren't shared between them.
The project numbering by default is 'By largest number.' For example, if you have a project with the number 100, and you create a new project and change the number to 200, the system will pick up the number 200 and add "+1" to the next project you will create. So, the next project's number will be 201.