Do I need a form to avoid paying duty on personal effects when returning to Thailand with my Thai spouse?

The user is returning to Thailand with their Thai wife after 20 years, carrying around 150kg of personal belongings. They seek clarification on whether they need a form to avoid customs duty on their items. Comments suggest that generally, there is no charge unless high-value goods are identified. Many expats recommend declaring items as personal effects and using multiple luggage carts. Others mention that Thai citizens can bring used household goods duty-free if certain conditions are met, but caution that customs may still charge duty on personal items. It may also be cheaper to buy new items in Thailand instead of bringing many suitcases.