Invoice Tax Updates Cannot Make an Invoice Total Negative
October 20th, 2026
POST /invoices/{invoice_id}/taxes now rejects taxes that would turn an invoice total that is zero or
positive into a negative total. The request returns 400 with the title NegativeInvoiceTotal and the
invoice is left unchanged. Review the taxes, or record the credit as a credit memo instead.
Invoices whose total is already negative can still have their taxes updated.
Applies to all API versions.