This can not happen. You can not change the taxes after having paid.
Taxes won’t change, but they will be associated with a party and such party can deduce them.
Last month I was in a big shop for electronics and bought some headphones, paid at the POS (point of sale) and asked for an invoice, after. Then I was directed to the service desk, where someone created an invoice based on my POS recipe.
The invoice describes it is only valid in combination with my POS recipe No 1234. The invoice doesn’t show VAT, but it stats that the VAT is declared on the POS recipe to avoid double taxing. So im my case the invoice is just another report based on the POS lines. I am sure this invoice doesn’t create any “account move lines” in the system of the electronics shop, because the move lines are already created by the POS.
I am not sure if this is just an additional way to create an invoice after paying at the POS or if it is the general way to create customer invoices for the shop.
The implementation in Tryton could be done by a new invoice type “Sale Point” which never produces any move/payment lines, but just adds an invoice line for each sale point line and shows the payment. A simple wizard in sale_point which asks the missing invoice parameter, party, address or just a text field for the invoice recipient and creates and prints the invoice without further notification.
The invoice recipient party could be created in the same step.
What do you think?
I do not think so because for me such sale converted to invoice must appear in the “EC Sales List”.
So the invoice must create the account move instead of the POS sale (which can not be posted yet) and include the payments.