Normally SAP does not encourage maintaining billing number range year wise. It should be a continuous one. But as you said, if it is a statutory law, then SAP should have considered that also but I am not sure.

Have a look at Note 1256346 - SAP Best Practices Baseline VN V1.603 whether it helps you.

In fact, In note 602901, following is mentioned

For other countries (for example Bangladesh, Pakistan,

Vietnam) SAP does not explicitely support country specific functions.

So better take up the issue with SAP in case the above notes are not answered your question.

thanks

G. Lakshmipathi