The final shipping amount is confirmed after your items reach the receiving location, are consolidated where applicable, and the parcel weight, dimensions, service, destination, and provider/carrier rate are known.
Current final-shipping payment is customer-present: K-Shippify shows the confirmed amount and the customer completes the checkout. K-Shippify does not currently auto-charge a saved card for final shipping.
Any preliminary shipping figure is informational unless the checkout identifies it as the confirmed amount. The amount and terms shown in the current final-shipping checkout govern that payment.