Coupon Code on invoices

[pfab]

We would like to have the ability for customers to enter coupon codes in their invoices.  We want to have a birthday code but our customers are usually recurring customers.  Offering a discount on their monthly services because its their bday would be awesome or our customers have the ability to use the coupon code on another invoice for services.  

[hammelcamel]

This needs to be added and standard practice. I would love this feature!

[THESTRANGE]

Any update to this addition? Currently 100% of our business using square is through invoicing. This would be a great marketing tool for us! I don't feel like there's much you could add to invoicing that's not already there so this is a big miss in my mind! Let's make this happen!😊