How Thailand's land and building tax is calculated

Under the Land and Building Tax Act B.E. 2562 (2019), tax is calculated from the assessed value published by the Treasury Department — not the actual sale price. This assessed value is usually lower than market price and is updated on its own revaluation cycle.

Owners can check their plot's assessed value on the Treasury Department's website or by asking at the local Land Office. The assessed value is expressed in baht per square wah or per rai, depending on location and land type.

The law splits rates into four broad categories: agricultural land (the lowest rate, with an exemption threshold for individual owners), residential land (with an exemption for a primary residence where the owner is on the house registration), land for other uses such as commercial or industrial (higher rates), and vacant or unused land (the highest rate, which increases further every 3 years if it stays unused).

Within each category, rates are also tiered by property value — the higher the value, the higher the per-unit rate. Exact current rates should be checked against the latest notice from the local administrative organisation, since they can be adjusted periodically.

The core formula is: tax due equals (assessed value per unit × land area) multiplied by the rate for that land-use category. Knowing the correct area — in rai-ngan-wah or square metres — is therefore the starting point for any rough self-estimate. Get the area right first at the land area converter.

Example: a 1-rai (1,600 m²) residential plot assessed at 3,000 baht per square metre has a total assessed value of 4,800,000 baht. If it doesn't qualify for the primary-residence exemption, that value is run through the tiered residential rate to find the tax owed.

A primary residence owned by an individual and listed on their house registration is usually exempt from tax on an initial slice of its assessed value. Agricultural land owned by an individual carries a similar exemption threshold. Exact conditions and thresholds can change under updated regulations. Housing estate plots fall under this same tax — see typical plot sizes in Standard plot sizes in Thai housing estates.

The figures here are a basic explanation for understanding purposes only, not an official tax assessment. Always verify the actual assessed value and rate with the local administrative organisation or municipality where the land sits before paying any real tax bill.

The assessed value used as the tax base is published by the Treasury Department's appraised-value lookup. The actual tax rate and any exemptions in force for a given year are set by the local administrative organisation where the land sits, since that's the body with authority to collect this tax.

Before paying, request an official tax assessment from the relevant municipality or sub-district administrative organisation to confirm the amount due, rather than relying on a rough self-calculation alone.

• Get the assessed value per unit from the Treasury Department — not the actual sale price.
• Convert the land area to square metres accurately before calculating anything.
• Multiply the assessed value per unit by the area to get the total assessed value.
• Check whether the plot qualifies for an exemption, such as a primary residence or agricultural land.
• Run the assessed value through the tiered rate for its land-use category, then confirm the final figure with the municipality before paying.