The Annual Value (AV) of a property in Singapore is determined based on the estimated annual rental value of the property, excluding rent for furniture, fittings, and service charges. For vacant land, the AV is determined at 5% of the estimated market price of the land. This system ensures that property tax is based on the rental value rather than the capital value of the property. The Property Valuation and Assessment Division of IRAS is responsible for assessing properties for property tax, ensuring a standardized and fair approach.