Non-taxable shipping method issue

Hi team,

I found what looks like a bug in stripe-tax-for-woocommerce affecting checkout totals when the selected shipping method is non-taxable.

Observed behavior:

• WooCommerce checkout shows the shipping line correctly, for example:
  • Product: $50.00
  • Shipping: $10.00
• But the returned order-review total is still $50.00 instead of $60.00
• Stripe payment initialization also reflects the wrong amount
• This only happens for a shipping rate set as non-taxable

The source of the problem seems to be in Stripe/Tax_Calculation/class-cart-input.php, where Cart_Input::get_taxable_shipping_cost_amount() only includes shipping cost when the chosen shipping method has tax_status = taxable.

The current logic:

• selected rate is loaded from chosen_shipping_methods
• plugin loads woocommerce_<method>_<instance>_settings
• if tax_status !== taxable, it skips that shipping amount entirely

That means non-taxable shipping is being excluded from the Stripe Tax cart input, so later in class-cart-controller.php, the set_total( $tax_calculation_result->amount_total ) method is called with a total that excludes shipping entirely, instead of including shipping as non-taxed.

There appears to be a matching pattern in Stripe/Tax_Calculation/class-order-input.php as well.

Expected behavior:

• Non-taxable shipping should still be included in the cart/order total
• It should simply not receive shipping tax

Suggested fix direction:

• Include chosen shipping cost in the Stripe Tax input regardless of whether the shipping method is taxable
• Only mark shipping as taxable / assign a shipping tax code when the method is actually taxable
• For non-taxable shipping, pass the amount through but omit taxability so tax remains zero

Hope this helps get a quick fix since we’re having issues where our orders are coming in with $0 as the shipping cost and we’re having to assume those costs.