Koh Samui Property Due Diligence Checklist 2026

Due diligence is the single most important step in any Koh Samui property purchase. This checklist covers every check that a competent property lawyer should perform before you commit.

1. Title Deed Verification

• Title deed grade confirmed — Chanote (NS4J) is the only title that carries full freehold rights; NS3 titles have boundary and third-party encroachment risks
• Land Office official search — physically verify the title at the Koh Samui Land Department, not just a photocopy from the seller
• Registered owner matches seller — ID of seller must match the name on the title; power of attorney must be verified if a representative signs
• No mortgages or encumbrances registered against the plot
• No disputes or legal cases noted against the title
• Plot area matches listing — measure against the title coordinates; discrepancies of 5–15% are common on older titles

2. Building and Planning Compliance

• Building permit obtained for all structures on the property (Aor-Bor-Tor 1)
• Certificate of Occupancy (Aor-Bor-Tor 6) issued for the main dwelling
• No unpermitted extensions — additional structures added without permits create legal liability for the buyer
• Zoning compliance — confirm the property is in a residential zone (Koh Samui’s yellow zone) or mixed-use zone, not a restricted conservation area
• Setback compliance — Thai building codes require minimum setbacks from plot boundaries, roads, and coastlines

3. Coastal and Environmental Restrictions

• Not within 50 metres of the high-tide mark — structures within this zone are illegal under the Enhancement and Conservation of National Environmental Quality Act
• Not within a national park buffer zone — parts of Koh Samui’s interior and coastline near Ang Thong Marine Park are restricted
• No active flood zone designation — Maenam and Bang Rak low-lying areas have experienced flooding; verify with local authority
• Not designated agricultural land — certain plots carry use restrictions that preclude residential development

4. Access and Utilities

• Legal road access confirmed — the approach road should be a public road or have a registered easement (Ni-Thi-Kamm) — private informal tracks are legally precarious
• Electricity connection — Provincial Electricity Authority (PEA) metre is installed and in good standing, not a shared connection
• Water supply — tap water connection confirmed; well-water properties require water quality testing
• Internet connectivity — fibre availability confirmed (critical for rental yield)
• Waste management — sewerage system or legal septic installation

5. Company-Held Properties (Additional Checks)

If buying a property held by a Thai company:

• Company registration — confirmed active and in good standing with the Department of Business Development
• Shareholder register reviewed — no nominee shareholder arrangements; genuine Thai shareholders with documented financial capacity
• Corporate tax compliance — Revenue Department returns filed for all operating years; no outstanding tax liability
• Company accounts — audited financial statements reviewed for hidden liabilities
• Director and shareholder minutes — annual meetings conducted and documented
• No pending litigation against the company

6. Financial and Transaction Checks

• Juristic person debt (for condominiums) — confirm no outstanding maintenance fee arrears on the unit
• Common area fund (for condominium developments) — sinking fund and maintenance reserves are adequately funded
• Property tax (Land and Buildings Tax) — confirm no arrears owed by the current owner
• Utility bills — electricity and water accounts in good standing with no outstanding balances

7. Condominium-Specific Checks

• Foreign quota — confirm building has not exceeded 49% foreign ownership
• Juristic person financial health — request last 2 years of juristic person accounts
• Pending special assessments — confirm no major repair levies are planned that would fall due post-completion
• Developer track record — for off-plan or pre-completion units, research the developer’s completion history

8. Rental Property Specific Checks

If purchasing primarily as a rental investment:

• Hotel licence — properties renting for periods under 30 days technically require a hotel licence under the Hotel Act; confirm licence status or risk
• Homeowner Association rules — some developments prohibit short-term rental; confirm rental policy before purchase
• Existing rental agreements — review and understand any active rental contracts that will survive transfer

Working through this list before signing any binding agreement will protect your investment and give you negotiating leverage on any issues uncovered. Our recommended legal partners in Koh Samui can conduct every item on this checklist. Contact us to be introduced to a vetted property lawyer.