The due date on an invoice is as provided by the billing party.

However, the due date should not be relative to the date provided, but the date presented to the payer.

For example, I have an invoice with a date of 1/29/21 which wasn't presented until 3/09/21. The due date on the website AND the receipt should be the later of the due date provided by the billing party and the date the invoice was actually provided to the paying party.