It would be usefull to have some advanced invoices numbering possibilities, like:
- multiple invoice number series. with different prefixes etc...
- maybe, make it possible to bind this series to categories
- have dynamic fields in number prefix like year, month, week, day
- auto restart numbering on dynamic prefix change (ie. always start from 1 in new year)
And partially related to this is also:
- pro forma invoice type
- automatically generate and send invoice from pro forma invoice, when payment referencing pro forma invoice is received
Companies can have different invoice series, for different services/departments. Pro forma invoices with different invoice number, are usefull if you can not have 'holes' in invoices in your accounting - every invoice 'number' should be accounted, and if you have not payed invoice with VAT, you still have to pay VAT to tax service.
With pro forma invoice, company first make a proposal (pro forma) invoice, that is sent to customer and once its payed, normal invoice is issued.
IMHO, this is big use case for EU countries, and good opportunity for payed extension ;-)