The official document numbers used on import documents (document classes 50 and 51) also consist of three parts, but without hyphens, for example, 123991234567890. The first part is a three-digit code that shows which customs office issued the document (here, 123). This number also indicates the document's class: there is only one office that issues documents of class 50, and only one that issues documents of class 51. The next two digits shows what year the document was issued in (1999), and the final part is a ten-digit running number (123456790).

When you post an import document, you enter the official number in a slightly different format from the norm because the Reference field is only 16 digits long. You enter the document class first, followed by a hyphen, followed by the ten-digit running number. So for a document whose official number is 123981234567890, you would enter 50-1234567890, 50 being the document class.

In reports, the system interprets these abbreviated numbers (calculating the customs office from the document class and the year from the document itself) and prints the official document numbers in full.

When you post a document manually, the system can automatically check the format of the official document number. To define which document types you want the checks to cover, in Customizing for Financial Accounting, choose Financial Accounting Global Settings ® Document ® Document Header ® Check Assignment of Document Class to Document Type.

In Peru, a delivery note has to include the official document number of the corresponding invoice and vice versa. The system cannot meet this requirement in full, since it cannot tell when printing out the first document which form will be used for the second. It can, however, show the official document number of the first document when printing out the second.