does square allow you to apply coupon to subtotal?

Hi,

Yes it is possible to apply coupon code with your form.

Please go through the below guide on how you can add coupons to your square payment integration.

https://www.jotform.com/help/233-how-to-add-coupon-code-to-payment-forms/

Please feel free to reply on us on the thread if you face any issue or need any help.

Thanks,

Ravi_G