The invoice numbers will be placed in a column (a list of invoice numbers), or will be in a single cell? The second option can be done only with a macro.
For creating consecutive numbers in your desired structure, you can use a formula like this:
=IF(LEN(A2)>0;YEAR(NOW())&"-"&TEXT(SUBTOTAL(3;A$2:A2);"00#");"")
(change ; separator to your regional settings)
Copy formula to your range...

Attached Files

New Microsoft Excel Worksheet.xlsx (9.6 KB, 48 views)