Deduct sale from coupon total

Hi

Is it possible to create a coupon voucher for lets say $ 1000 if a person then makes a purchase of $100 they are left with a coupon to the value $900 they can then make another purchase of $400 which leaves them with a coupon that has $500 remaining on it

Hello,

Coupons will only have fixed values for each use during the checkout workflow, so it will probably require code customization to create that kind of option.