Does your Koh Phangan project need an EIA? The room-count and area thresholds that trigger it

At what size does a villa or resort project on Koh Phangan need an environmental assessment before it can get a building permit? Nationwide, a hotel or condominium triggers a full Environmental Impact Assessment (EIA) once it reaches 80 rooms/units or 4,000 m² of usable area, reviewed by the Office of Natural Resources and Environmental Policy and Planning (ONEP). But Koh Phangan — along with Koh Samui and Koh Tao — sits inside a Ministry-designated Environmentally Protected Area under Surat Thani province, the same framework behind the island's 2025 building zones (see Building zones on Koh Phangan). Inside that zone, a lighter-weight Initial Environmental Examination (IEE) kicks in at a much lower threshold — a detail Building a villa on Koh Phangan flags in passing as a ≥50-room trigger; this guide sets out the full mechanism behind it.

Two tiers: IEE vs. full EIA

• IEE (Initial Environmental Examination) — the lighter study required inside a designated Environmentally Protected Area, under the Enhancement and Conservation of National Environmental Quality Act B.E. 2535 (1992). Since a September 2024 ministerial regulation, hotels with 1–49 rooms are exempt; 50 rooms and up in a protected area need an IEE — up from the previous 29-room exemption line.
• Full EIA — triggered nationwide, protected area or not, once a hotel or condominium reaches 80 rooms/units or 4,000 m² of usable floor area, whichever comes first, reviewed by ONEP's expert committee rather than the lighter local process.
• Housing estates and land subdivisions run on a separate, plot-count-based licensing regime under the Land Development Act instead of this EIA/IEE framework — see Subdivided land and the Land Development Act.

Who reviews it, and how long it adds

ONEP receives and processes the report; an expert review committee — ONEP plus the relevant licensing authority and outside specialists — evaluates it, typically targeting a decision within around 60 days for a straightforward case. This runs on top of, not instead of, the Building Control Act's own 45-day permit-review window covered in Building a villa on Koh Phangan; that guide's 6–14 month estimate for projects needing environmental review reflects the two processes combined, not the assessment alone.

Building before approval is a separate offence

Section 101/1 of the National Environmental Quality Act (added in the 2018 amendment) makes starting construction before EIA or IEE approval its own offence, distinct from ordinary Building Control Act penalties: a fine of up to ฿1,000,000, plus a further fine of up to ฿100,000 for each day the violation continues, rising to 1.5 times those amounts if the project is classified a "significant project." This stacks on top of — not instead of — the demolition-order and fine exposure an unpermitted building already carries.

Why this matters for a buyer, not just a developer

• Ask specifically whether a project's room/unit count or usable area crosses either threshold, and if so, request the IEE or EIA approval letter itself — not just the building permit. See Vetting an off-plan project.
• Sitting just under 50 rooms doesn't exempt a project from the building-control process — only from this specific environmental layer.
• Given the island's active pipeline (see Koh Phangan's 2025–2026 development pipeline), several current and planned projects are sized to sit inside this regime — worth asking about before paying a deposit, not after.

For a single private villa, this rarely applies — the thresholds are built around hotels, condominiums and larger developments. But for anyone buying into a resort-style or larger residential project, the IEE/EIA approval is a genuine, checkable document, and its absence on a project large enough to need one is a real red flag, not a technicality.