How do I handle CH↔EU cross-border shipping (DDP) in Magento?

Switzerland is not in the EU customs union, so every CH↔EU parcel crosses a customs border. For premium DTC (luxury, watches, fashion), DDP (Delivered Duty Paid) is the expected default — the seller pre-pays VAT + customs so the customer never sees a surprise bill at the door. Two-part Magento setup:

1. Pricing engine — we add an EU-VAT calculation layer (per destination country: DE 19%, FR 20%, IT 22%, NL 21%, etc.) on top of CHF list prices, and quote “CHF X (DDP, all duties included)” in checkout.
2. Carrier rules — Swiss Post + DHL CH both offer DDP-bonded labels with the right HS commodity codes per SKU. We populate product_attribute with HS codes (8-digit), country-of-origin, and net weight, and the carrier module emits the right CN23 / commercial-invoice docs.

For low-value parcels (< EUR 150), IOSS to EU is optional; for >EUR 150 it’s mandatory full customs clearance.