What are the rules for duty-free shipments when moving to Thailand on a long-term visa?

When moving to Thailand, the duty-free shipment allowance is contingent on the type of visa held. It's generally available only if you have a work permit, and the goods must be declared as personal effects, not new items. Most experiences indicate that customs fees aren't usually applied if properly declared, but there are no allowances for various visa types, such as the Retirement Visa or a tourist visa like DTV. Users suggest transporting items in your luggage or purchasing new items in Thailand instead.