Subtotal in the cart doesn't change on applying a coupon.
Is it possible for Subtotal to be: (order total - coupon discount) - tax ?
No Subtotal in the cart doesn't changes on applying the coupon code as per the Ecommerce standards.
- The flow is:
This is what the complete picture looks like.
The (order total - coupon discount) -tax you are looking for is Grand total. But if you want, you can use some custom extensions.