Illegal construction crackdown in Koh Phangan's forest reserves and hillsides: what a buyer needs to know

Is it actually illegal to build inside Koh Phangan's forest reserve or on a graded hillside without checking the boundary first? Yes — and in September 2025 Surat Thani authorities found out how common it had become. Inspectors discovered at least five buildings already standing inside the island's national forest reserve, plus cleared and graded hillside land with groundwater wells drilled ahead of further construction. The case is now one strand of a wider 2025–2026 enforcement campaign that should change how any buyer checks a plot before committing.

What was found

• At least five buildings confirmed built inside Koh Phangan's national forest reserve during September 2025 inspections.
• Adjacent hillside land cleared and graded for vehicle access, with wells drilled — signalling further construction was planned before the enforcement action.
• A dedicated task force under the Fourth Army Region carried out the investigation, at the direction of the Surat Thani governor, who ordered agencies to accelerate the review with a focus on foreign nationals and nominee operations.

How investigators are documenting the violations

Inspectors are using aerial photography and GPS mapping to record the exact footprint of cleared and built areas, cross-referencing the results against the surveyed forest-reserve boundary before submitting findings to the Surat Thani governor for legal action. This is a materially more rigorous method than a single site visit — it produces a defensible geographic record that can support prosecution and demolition orders.

The legal exposure

Building on or holding land inside a reserved forest without a specific statutory right is a criminal offence under the National Reserved Forest Act B.E. 2507 (1964). Enforcement precedent elsewhere in Thailand shows this exposure is real even where a title deed exists: in a widely cited Phuket case, the Supreme Administrative Court ordered a hotel demolished after finding the underlying land certificate had been unlawfully issued over forest land. Since 2020, Thailand's national parks authority has demolished or ordered the demolition of more than 20 luxury villas, resorts and hotels found illegally built inside national parks in the Western Forest Complex alone — a title document did not protect any of them.

Part of a wider enforcement wave

The forest-reserve findings sit alongside a broader nominee-ownership crackdown running across Koh Phangan and Koh Samui through late 2025 and into 2026: a first round of raids targeted 32 companies with apparent nominee structures across 45 land plots (more than 40 rai), with damage assessed above ฿200 million and 22 foreign arrests; a second phase involved more than 300 officers. See Nominee-ownership crackdown: what it means for island buyers. The pattern in both strands is the same: authorities are now cross-referencing land registry, corporate and geographic data rather than relying on paperwork presented at the counter.

What this means before you buy

• A title deed is not proof a plot sits outside the forest reserve. Elsewhere on the island, a Nor Sor 3 Gor title has been found issued over land suspected of encroaching on forest-reserve boundaries — see Chanote vs Nor Sor 3 Gor in practice.
• Check the plot against the Royal Forest Department's reserve boundary, not just the cadastral map, before signing anything — a Thai lawyer or licensed surveyor can request an overlay.
• Treat 'already cleared' or 'already has a well' as a red flag, not a selling point, on hillside or forest-adjacent land — that is precisely the pattern investigators are now targeting.
• Any structure already built without this check carries real demolition risk, regardless of how long it has stood or what a seller claims about its permit status.

None of this changes how a compliant purchase works — a verified title, a confirmed zone, and a properly registered lease and superficies remain the standard, safe route; see Building a villa on Koh Phangan and the due diligence checklist. It does mean that boundary verification against the forest reserve is no longer an optional extra for hillside or interior land — it is now an active enforcement risk.