SKULabs offers third-party billing feature for shipping carriers connected through EasyPost. The very first step to start using third-party billing is to contact SKULabs support and request for your account to be enabled to use the third-party billing feature.
Next, follow these steps to set up third-party billing:
Connect carriers to SKULabs via EasyPost
Add each of your third-party’s accounts over at https://app.skulabs.com/settings#shipping/third_party_billing
Create shipping rules at https://app.skulabs.com/settings#shipping/rules and configure rule criteria so that the appropriate orders get billed to the appropriate party. Use Set Third-Party Billing Account as the shipping rule's action.
Please contact SKULabs support for more information or if you would like assistance.