Calculate free ship total after coupons

I have my site setup to do free shipping on $20 or more. I wanted to offer a generous free ship option and I crunched the numbers and felt comfortable with $20. The issue I am having is I run coupons a lot and zen cart gives free shipping on the total before coupon. If I have someone order $20 worth of product but then use a 20% discount the total is now $16. I don't want this to get the free ship option but it does. This is hurting me on smaller orders and really want to change it but I can't find any options for this.

Can anyone help fix this so zen cart gives free shipping on the final total. I thought this would be an option. I would think a lot of people would want to set it up like this

Are you doing Free Shipping with the Modules ... Order Total ... Shipping ot_shipping or what method are you giving your Free Shipping? :lookaroun

I am using the "free shipping offer" module. I have looked over the settings available for this and don't see a way to set this so it calculates after coupons.

I have it set to equal or greater then $20

I have still never solved this issue. Is there a way to have free shipping calculate off the final price after coupon? I don't understand why the free shipping goes off the pre coupon totals

mysh:

I have still never solved this issue. Is there a way to have free shipping calculate off the final price after coupon? I don't understand why the free shipping goes off the pre coupon totals

Yes there is, the hard code needs to be modified to subtract the coupon from the subtotal, then present the shipping options you have installed... based on their relative settings.

I'm not great with code but I can do some modifications if pointed in the right direction. Is there any tutorial or webpage that describes how to do this?

It needs to be custom coded... :)