Start with the rent actually collected in a year, allowing for empty periods. Deduct:

  • common-area fees and any sinking fund top-up
  • letting and management fees, or the operator's share in a rental programme
  • utilities and internet where the owner pays them
  • insurance, repairs and periodic replacement of furniture and air conditioning
  • land and building tax
  • income tax on the rent, including the 15% withheld from rent paid to a non-resident owner

Divide the result by what the property really cost: the price plus transfer fees, legal fees and furnishing.

As an illustration, a unit that cost THB 10.4 million including buying costs and collects THB 600,000 in rent, with THB 180,000 of annual costs and tax, has a net yield of about 4%. The same unit would be advertised at a gross yield of 6%.

Net yield is still not the whole return. It ignores changes in the property's value and in the exchange rate between the baht and your home currency. See rental yields in Thailand and the rental yield calculator.