Why is there an option to Allow customer to save a card on file when creating an Invoice from the Square Dashboard, yet no option to include this from the Invoices API? I have seen other replies from Square to this same question, yet to say “save card on file isn’t currently available” is insufficient. This needs to be in the invoice API now. When are you going to complete this?
We’re constantly working to improve our features based on feedback like this, so I’ll be sure to share your request to the API product team. 
Hey @ecox! Just wanted to update you that we now support being able to store a card on file using the Invoices API.
As of API version 2022-09-21, you can just specify true on the store_payment_method_enabled field when creating an invoice to allow the buyer to have the option to store their card info when paying the invoice.