I also doubt anything to do with accounting, or figures and reports.
Possibly cash flow, and it does seem a bit much having them falling due more than a month before your current subscription.
My initial thoughts were that it was out of courtesy more than anything else. Personally I find it more rude to receive an invoice when a subscription has ended, particularly if it is a large amount and due for payment immediately.
Not sure where cash based VAT reporting comes into it. Did I miss something?
David Toohey
The Accountants Circle