3rd party shipping rates not updating when a customer applies a discount at checkout

Hi there. I am looking for some help configuring variable shipping rates based on location and cart value.

We have looked at two different 3rd party shipping apps (Shipeasy & Postcode Shipping). Both apps are from the Shopify app store and are able to deliver the below scenarios effectively based on the cart value (note: I am referencing cart value, not checkout value).

Location (based on postcodes) Cart < $60 Cart > $60
Zone 1 & 2 $7.50 FREE
Zone 3 $15 $10

The challenge we have is when someone has a cart above $60 (triggering free or reduced postage) and then includes a discount at checkout (which we offer first time customers for example), reducing their checkout cart value below $60. Given the Checkout API is no longer available for 3rd party shipping apps, the updated fee is not available for the shipping app to adjust the rates as per the table above. Therefore, a customer who has a cart value of say $70 (therefore eligible for free postage) who applies a 20% discount code (reducing their cart to $56) would still be eligible for free postage despite their cart value being < $60.

I am also aware that the easiest approach here would be to give everyone free postage > $60, but we need variable rates by zone, as zone 3 is rural shipping in Australia and typically very expensive for postage. Otherwise, we would just make it free for everyone above $60 and use the standard Shopify discount option.

Has anyone come across a similar situation and found a solution to meet this requirement?

Thanks in advance for everyones help!

Hello @JordyPakes ,

Can you please share your Shopify store name?