In Thailand, a "proposed address" is the location you intend to use for official purposes (business registration, bank account, etc.). It should follow the standard Thai address hierarchy:
123/45 Soi Prasert-Manukitch, Bang Kapi, Huai Khwang, Bangkok 10310, Thailand
Ensure consistency across all documents. Verify the postal code via Thailand Post or local post office. Consult the requesting authority if unsure.