Inheritance tax on Thai property: the 100-million-baht threshold most villa owners' estates never reach

Will your family owe Thai inheritance tax on your villa when you die? For the overwhelming majority of Phangan buyers, no — Thailand's Inheritance Tax Act B.E. 2558 (2015), in force since 1 February 2016, only taxes the value a single heir receives from a single deceased person above ฿100 million, and even then only the excess over that line. Below it, nothing is owed, and there's no requirement to file at all.

Who's actually liable

• Thai nationals — taxed on worldwide inherited assets.
• Foreigners domiciled in Thailand under immigration law — also taxed on worldwide inherited assets, not just Thai ones.
• Any foreign heir, wherever they live — taxed on assets situated in Thailand at the time of death, including a Phangan villa's land and building. Living abroad and never having set foot in Thailand doesn't exempt an heir from tax on a Thai-situated inheritance.
• A spouse of the deceased — fully outside the Act; spousal inheritances are exempt entirely, at any value.

The threshold is per heir, per deceased person — not per estate

The ฿100 million line isn't a single number applied to the whole estate; it's tested separately for each heir, against everything that heir receives from that particular deceased person, whether in one transfer or several over time (Section 12). If a parent leaves a villa worth ฿60 million and a bank deposit worth ฿50 million to a single child, that child's combined inheritance from that parent — ฿110 million — is what gets tested. Split the same estate three ways among three children instead, and each child's individual share may sit well under ฿100 million and owe nothing.

How the villa itself is valued

For immovable property, the Act values the inheritance at the Land Department's official appraised value used to calculate transfer fees — the same conservative government figure used throughout a purchase, not the market price a buyer would actually pay (Section 15). Appraised values on Koh Phangan typically run well below transaction prices; see The full cost of buying on Koh Phangan for how that gap plays out at purchase. Outstanding third-party rights on the property — a registered mortgage, for instance — are deducted from that appraised value before the threshold test is applied. In practice, this appraisal gap is the main reason a villa that would sell for well over ฿100 million on the open market can still land an heir under the tax-free line.

Rates — and only on the amount over the line

• 5% — where the heir is an ascendant or descendant of the deceased (a parent, grandparent or child).
• 10% — every other heir, including siblings, other relatives and unrelated beneficiaries.
• Either rate applies only to the value above ฿100 million, not the full inheritance — an heir receiving ฿120 million from a parent owes 5% of ฿20 million, not of the full amount.

What counts as taxable inheritance

The Act covers immovable property, listed securities, bank deposits, registered vehicles and other assets the government designates by Royal Decree (Section 14). A leasehold villa is more layered than an outright freehold: the lease, the building and any Thai company shares behind the structure can pass to heirs in different ways and are governed separately from whether tax is owed on them — see Inheritance on Koh Phangan: what happens to your leasehold and villa when you die for how each piece actually transfers.

Filing and payment, if the threshold is crossed

• 150 days from receiving the inheritance to file a return and pay, using the Revenue Department's prescribed form at any Area Revenue Branch Office (Section 17).
• Multiple heirs must agree on one person to file; without agreement, any heir can petition the court to appoint an estate administrator (Section 19).
• Installments over up to 5 years are available under Revenue Department rules — pay on schedule and the surcharge is waived entirely for plans of two years or less, and only partially applied for longer plans (Section 23). That matters when the estate's main asset is the villa itself and the cash to pay tax isn't sitting in a bank account.
• Missing the deadline adds a surcharge plus a penalty equal to the tax owed (double if paid only after an assessment is issued) — the tax due itself is unaffected either way (Section 18).

None of this changes the separate, more common planning question: whether your heirs actually receive the lease, the building and the company shares smoothly, which depends on contract wording and succession clauses, not on this tax. Pair this with a registered Thai will — see Thailand's 2026 will registration rules — so the mechanics of transfer are settled well before the ฿100 million question ever comes up. Right Way doesn't file tax returns for clients; for the small minority of estates that do cross the threshold, a Thai tax lawyer should confirm the valuation and filing before the 150-day clock runs out.