Koh Samui Property Due Diligence Checklist: 15 Things to Verify Before You Buy

Disclaimer: This guide is for informational purposes only and does not constitute legal advice. Laws and regulations change frequently. Consult a qualified Thai property lawyer before making any purchase decisions. Samui Property Group recommends engaging an independent, bilingual attorney with verifiable Koh Samui transaction experience.

Buying property in Koh Samui is one of the most exciting investments you can make — and one of the most consequential. The island’s luxury villa market, hillside sea-view estates, and beachfront condominiums attract buyers from across the globe, but Thailand’s property legal landscape contains layers of complexity that can trap the unprepared.

This checklist exists because due diligence is not optional. In Koh Samui specifically, unique local factors — water supply vulnerabilities, steep hillside construction, seasonal flooding in low-lying areas, coastal setback enforcement, and the island’s history of irregular land documentation — make thorough verification non-negotiable before any purchase. Samui Property Group has compiled these 15 items as the definitive pre-purchase framework for international buyers. Work through every item, ideally with an independent Thai property lawyer at your side.

For a broader introduction to foreign ownership in Thailand, see our guide: Can Foreigners Buy Property in Koh Samui? The Complete Legal Guide.

The 15-Point Koh Samui Due Diligence Checklist

1. Verify the Title Deed Type

The title deed is the single most important document in any Thai property transaction. Not all title deeds carry the same legal weight, and the type of deed directly determines your rights, your ability to secure financing, and the enforceability of any registered encumbrances.

Thailand’s Land Department issues several categories of land document. Only two are truly suitable for serious property investment:

Chanote (Nor Sor 4 Jor) — The Gold Standard. The Chanote is the only true freehold ownership document in Thailand. Land boundaries are precisely measured using GPS and satellite imagery, with physical marker posts set in the ground at each corner. The title is tied to the national survey grid. All legal acts — sale, lease, mortgage, usufruct — can be executed immediately without public notice periods. Banks will lend against Chanote-titled land. According to Siam Legal International, only the Chanote (Nor Sor 4 Jor) constitutes a certificate of true land ownership.

Nor Sor 3 Gor — Acceptable, But Verify. A Nor Sor 3 Gor has been officially surveyed and boundaries confirmed, but it has not yet been upgraded to a full Chanote. It can be sold, transferred, leased, or mortgaged in the same manner as a Chanote, and no 30-day public notice period is required for transactions, per Siam Legal International. Banks will generally lend against this title. Owners can petition the Land Department to upgrade to Chanote.

Nor Sor 3 — Proceed with Caution. The Nor Sor 3 confirms possession but not true ownership. Crucially, the land has never been officially measured by the Land Department, so boundaries are approximate and disputes with neighbouring landowners are common. Any sale or transfer requires a 30-day public notice period during which third parties can file objections, according to Thailand Law Online. Most banks will not lend against Nor Sor 3 titles.

Sor Kor 1 — Walk Away. A Sor Kor 1 is a certificate of land use, not ownership. It establishes only a claim of possession — not actual ownership — and no legal rights such as sale, lease, or mortgage can be registered over this category of land, per Benoit & Partners. Avoid entirely.

Action: Request the original title deed. Your lawyer must conduct a physical title search at the Koh Samui Land Department office to confirm authenticity. Fraudulent title deeds, while uncommon, do exist — only a Land Department search provides 100% certainty.

2. Confirm the Seller’s Legal Right to Sell

Even a valid Chanote title deed does not automatically guarantee that the person offering to sell it has the right to do so.

• Name match: Verify that the name on the title deed exactly matches the seller’s identification documents. Discrepancies — including name changes, transliteration differences between Thai and English — must be explained and documented.
• Co-ownership: Check whether the title deed lists multiple owners. All registered co-owners must consent to and sign the transfer documents. A single co-owner cannot unilaterally sell shared land.
• Power of Attorney: If an agent or representative is acting on behalf of the registered owner, insist on seeing a notarised, authenticated Power of Attorney. Your lawyer must verify it is current, properly executed, and covers the specific transaction.
• Court orders and disputes: Your lawyer should check with the Koh Samui Provincial Court for any injunctions, seizure orders, or ongoing disputes attached to the title or the seller personally. Outstanding court orders can prevent transfer even if the title appears clean.
• Company-owned property: If the seller is a Thai Limited Company, extensive additional due diligence is required — corporate affidavit, full shareholder list, director authorisation resolution, and financial records must all be verified. See our guide: Koh Samui Property Ownership Structures Explained: Leasehold, Freehold, and Thai Company.

3. Search for Encumbrances at the Land Department

The reverse side of a Thai title deed records all registered legal burdens on the land. Your lawyer must physically inspect the title at the Land Department — not just a copy provided by the seller — to read the full encumbrance record.

Common encumbrances to check for include:

• Mortgages: Any outstanding mortgage must be formally discharged and cancelled at the Land Department on or before the day of transfer. The seller is responsible for clearing any mortgage, typically from sale proceeds. Never proceed to transfer with a registered mortgage still in place.
• Liens and judicial charges: Court-ordered liens or debt enforcement orders can freeze transfer.
• Servitudes and rights of way: Neighbouring landowners may have registered rights of way or utility easements across the land. These run with the land and bind any new owner — they cannot be cancelled simply because ownership changes.
• Usufructs and superficies: Long-term registered use-rights in favour of third parties may encumber the property for decades. Verify these are disclosed and negotiated before signing any purchase agreement.
• Lease registrations: Registered leases, even long-term ones, are encumbrances. If a property carries an existing registered lease, understand the terms — including remaining duration and transferability — before proceeding.

4. Verify the Land Boundaries Match the Title

On Koh Samui, boundary discrepancies are a persistent and expensive problem. The island’s rapid development history, mountainous terrain, and legacy of less rigorous survey standards mean that what is described on a title deed and what physically exists on the ground do not always match.

• Physical survey: Commission an independent licensed surveyor to physically walk the boundaries and confirm they align with the title deed measurements. Do not rely solely on the seller’s representations.
• GPS survey for hillside plots: For hillside properties — particularly those above 80 metres elevation — a GPS survey is essential to confirm plot coordinates against the national grid.
• Boundary markers: Confirm that all concrete or metal survey posts referenced in the Chanote are physically present and undisturbed. Missing or relocated markers warrant investigation.
• Neighbour encroachment: In older developments and informal residential areas, neighbour encroachment (a structure, fence, or driveway extending over the boundary) is common. Identify any encroachments before purchase, as rectifying these after transfer falls to the new owner.
• Road access: Confirm the property has legal, registered access to a public road. Land-locked plots — where access depends entirely on permission from a neighbouring landowner — carry significant risk and should be avoided unless formal easement rights are registered on the title deed.

5. Check Zoning and Land Use Regulations

Koh Samui has a detailed zoning system that determines what can be built, where, and at what density. Misunderstanding zoning is one of the most common mistakes international buyers make — particularly those planning development or commercial use.

Colour zones on Koh Samui, as administered by the Koh Samui Municipality (Or Bor Tor) under Thailand’s Town Planning Act B.E. 2518, include:

• Green Zone (Zones 6.1–6.9): Low-density residential. Primarily suited to villas and single-family homes.
• Yellow Zone (Zones 1–1.20): Residential and condominium development. Suitable for foreign condominium quota projects.
• Orange Zone (Zones 2–2.4): Medium-density residential and tourism. Other uses must not exceed 20% of total land area.
• Red Zone (Zones 3.1–3.11): High-density residential and commercial. Commerce, hospitality, and tourism permitted.

Coastal setback rules are strictly enforced under Thailand’s Building Control Act, as explained by Benoit & Partners:

• Within 10 metres of the beach: No construction permitted.
• 10–50 metres: Single-storey only; maximum 6 metres height including roof; maximum 75 sqm floor area.
• 50–200 metres: Maximum 12 metres height; maximum 2,000 sqm footprint.
• Beyond 200 metres: Maximum 12 metres height; no footprint restriction beyond other planning rules.
• All roofs must be pitched or sloped; flat roofs are not permitted.

Elevation restrictions add another layer:

• Below 80 metres ASL: General rules apply; hotels must leave 50% of land as green space.
• 80–140 metres ASL: Single-family homes only; maximum 6 metres height; minimum 400 sqm land area; minimum 50% land left green; traditional Thai/tropical architectural style required.
• Above 140 metres ASL: Same as above plus maximum 90 sqm building footprint.

Slope restrictions:

• 35–50 degree slopes: Single-family homes only; maximum 80 sqm; minimum 75% land left unbuilt.
• Above 50 degrees: Construction strictly prohibited.

Confirm zoning at the Koh Samui Municipality (Or Bor Tor) office. Your lawyer should obtain written confirmation of the applicable zone and all restrictions relevant to your intended use before exchange of any purchase agreements.

6. Confirm Building Permits and Construction Licenses

The existence of a building does not mean it was legally constructed. Illegal construction — including structures built without permits, additions beyond approved plans, and buildings in restricted zones — is a documented problem on Koh Samui, as Channel NewsAsia has reported in its coverage of the island’s development challenges.

Your lawyer must verify:

• Ror. 4 construction permit (Bai Anuyat Ko Sang): This is the primary building permit issued before construction begins. Confirm it was obtained, matches the structure as built, and was issued by the correct authority.
• Compliance with approved plans: The issued permit must be compared against the actual structure. Illegal additions — extra floors, extensions, swimming pools, guest annexes — that were built without permit approval create liability for the buyer post-transfer.
• Municipal office (Or Bor Tor) verification: Your lawyer should physically visit the Or Bor Tor to obtain copies of all issued permits. Do not accept photocopies provided solely by the seller.
• Swimming pools and ancillary structures: Swimming pools, sala pavilions, and guesthouses require their own separate permits. Verify each structure individually.
• Demolition risk: Structures built in clear violation of Koh Samui’s coastal setback or elevation rules are subject to demolition orders. Purchasing an unpermitted structure in a restricted zone can result in mandatory demolition at the new owner’s expense.

7. Environmental and Geological Assessment

Koh Samui’s physical geography creates property risks that do not appear in any legal document. Before purchasing any property — particularly hillside villas or properties in low-lying coastal areas — commission an independent environmental and geological assessment.

Flood risk: Low-lying areas on Koh Samui, particularly Bophut, Maenam, and parts of Chaweng Beach Road, have a documented history of serious flooding during the island’s wet season (October–December). Flash flooding can reach depths of one metre or more in affected areas. Koh Samui has been declared a disaster zone following exceptional rainfall events, as Channel NewsAsia has reported in its coverage of the island’s climate and sustainability challenges. For investment properties intended for year-round rental, flood risk directly affects rental income, maintenance costs, and insurability.

Landslide risk: Thailand’s Department of Natural Resources and Environment has issued repeated warnings about landslide risk on Koh Samui’s hillsides, particularly where deforestation and steep-slope construction have disrupted natural drainage. Properties on slopes between 35 and 50 degrees are subject to strict build restrictions; slopes above 50 degrees prohibit construction entirely. An engineering soil stability assessment is advisable for any hillside purchase.

Drainage systems: Confirm that the property has adequate storm drainage. Verify that neighbouring constructions have not blocked natural drainage channels — a known contributor to flooding in developed areas.

Protected forest zones: Koh Samui’s mountain and forest areas include 23,546 rai designated as protected forest zone. No title deeds should be issued for land within these zones. Your lawyer must confirm the property’s land classification does not encroach on protected areas.

Coconut tree preservation: Koh Samui has local preservation considerations relating to coconut palms that may affect development plans. Confirm with the Or Bor Tor whether any coconut trees on or adjacent to the plot are subject to preservation orders.

8. Verify the EIA (Environmental Impact Assessment) if Applicable

For larger developments and properties in environmentally sensitive areas, an Environmental Impact Assessment (EIA) is required by law. Purchasing a completed or off-plan development that should have obtained EIA approval but did not is a serious legal risk.

According to Thailand’s Office of Natural Resources and Environmental Policy, EIA requirements apply to developments including:

• Hotels or resorts with 80 rooms or more, or at least 4,000 sqm of utility area.
• Condominiums with 80 or more units, or at least 4,000 sqm of utility area.
• Developments in environmentally sensitive or designated protection areas.

On Koh Samui specifically, hotel developments with more than 50 guest rooms or land areas of 2,500 sqm or more require an EIA or Initial Environmental Examination (IEE), as detailed by Benoit & Partners in their guide to property development in Thailand.

Action: Ask the developer or seller for the EIA approval certificate and the name of the approving authority. Your lawyer should independently verify the approval with the Office of Natural Resources and Environmental Policy (ONEP) or the Suratthani provincial environmental office. An unapproved development carries risk of enforcement action, fines, and potential compulsory demolition.

9. Check the Foreign Ownership Quota (Condominiums)

For foreign buyers purchasing a condominium unit under freehold ownership, the 49% foreign quota is the critical legal mechanism that makes the purchase possible — and its availability must be verified before any commitment is made.

Under Thailand’s Condominium Act B.E. 2522 (1979), foreigners may collectively own no more than 49% of the total sellable floor area in any single condominium building. This limit is calculated by floor area — not number of units. Large penthouses or duplex units take up a proportionally larger share of the foreign quota.

Key verification steps:

• Request a written quota confirmation letter from the condominium’s juristic person (management office) stating the current foreign ownership percentage and the available remaining quota.
• Verify at the Land Department: Your lawyer can independently confirm quota availability with the local Land Department.
• Check units in transfer process: Units already under contract for transfer to foreign buyers may already be consuming quota before they appear on the management’s records. Ensure any confirmation letter is current.
• Foreign Exchange Transaction (FET) Form: To register freehold ownership, the purchase funds must be remitted to Thailand from abroad in foreign currency and converted to Thai Baht. The bank will issue a Foreign Exchange Transaction Form (FET/Tor Tor 3), which is a mandatory document for the Land Department transfer. Budget for this documentation step early in the purchase process.

If a building’s foreign quota is already at 49%, the Land Department will refuse to register transfer into your name regardless of what any seller or developer has promised.

10. Review the Lease Agreement Thoroughly (Leasehold Properties)

Most villa and house purchases by foreign buyers in Koh Samui are structured as 30-year leaseholds, since foreigners cannot directly own land under the Land Code Act. The quality and terms of a lease agreement have profound implications for your security of tenure, your ability to transfer or mortgage the property, and what happens at the end of the term.

The 30-year maximum. Under Section 540 of Thailand’s Civil and Commercial Code, the maximum enforceable lease term for immovable property is 30 years. Leases exceeding three years must be registered at the Land Department (Section 538) to be enforceable beyond that three-year period.

The 2025 Supreme Court ruling on renewal clauses. In a landmark decision (Supreme Court Case No. 4655/2566), the Thai Supreme Court ruled that pre-agreed automatic renewal clauses — the “30+30+30” structures widely marketed to foreign investors — are void and unenforceable, as reported by Formichella & Sritawat Attorneys at Law and confirmed by Siam Legal International. The Court held that any lease arrangement attempting to extend beyond 30 years through pre-agreed renewals violates the mandatory statutory limit and constitutes an impermissible circumvention of the law. The initial 30-year term, if properly registered, remains valid — but promises of renewal beyond year 30 cannot be enforced.

What to verify in any lease agreement:

• Registration: The lease must be registered on the title deed at the Land Department. An unregistered lease is enforceable for only three years, regardless of the stated term.
• Term commencement date: Confirm the date from which the 30-year term runs. Some developers sign leases before construction is complete, reducing your effective tenure.
• Sub-lease rights: Confirm whether you have the right to sub-lease the property to tenants. Without this, operating a rental villa is legally problematic.
• Transfer rights: Confirm whether you can transfer (sell) the leasehold interest to a third party. A non-transferable lease has significantly diminished resale value.
• Termination clauses: Identify all circumstances under which the landlord can terminate the lease early. Broadly drafted termination clauses are a red flag.
• Renewal language: Post-2025 Supreme Court ruling, any “renewal” clause is an option only — not a guaranteed right. Understand that renewal at year 30 depends entirely on the goodwill of the then-current landowner.

For a full explanation of ownership structures, see: Koh Samui Property Ownership Structures Explained: Leasehold, Freehold, and Thai Company.

11. Investigate the Developer’s Track Record

For off-plan purchases or recently completed developments, the developer’s track record is as important as the property’s legal documents. Thailand’s property market has seen developers fail to deliver projects, complete them to substandard quality, or encounter financial difficulties that leave buyers in limbo.

Verify the following:

• Completed projects: Ask the developer for a list of completed projects with names, addresses, and handover dates. Visit at least one completed project in person to inspect build quality and speak with residents or owners.
• Delivery timelines: Late delivery of off-plan properties is common. Review whether prior projects were delivered on time, and examine any reported delays.
• Financial health: Your lawyer can request a company affidavit from the Department of Business Development (DBD), which shows the company’s registered capital, shareholders, and any registered liabilities. A developer with minimal paid-up capital relative to project scale is a risk.
• Court records: Your lawyer can check the Koh Samui Provincial Court for any litigation, bankruptcy proceedings, or judgment orders against the developer or its principals.
• Customer reviews: Online reviews, expat community forums, and Facebook groups covering Koh Samui property can surface first-hand buyer experiences. Look for patterns — not isolated complaints.
• Escrow and payment protection: For off-plan purchases, inquire whether payments are held in a protected escrow account or paid directly to the developer. Direct payment to a developer with no financial protection exposes buyers to significant loss if the developer defaults.

12. Assess Infrastructure and Utilities

Property values and quality of life on Koh Samui are directly affected by infrastructure realities that do not appear in any sales brochure. Verify each of the following independently:

Water supply: Koh Samui has a chronic and documented freshwater shortage. As Channel NewsAsia reported, a combination of drought conditions, unreliable infrastructure, and booming tourism has left authorities unable to reliably service the population. Private water delivery trucks are a daily reality for many properties, particularly in elevated areas where pipeline pressure is insufficient. For any villa purchase, ask:

• Is the property connected to the Provincial Waterworks Authority (PWA) supply?
• Does the property have its own private deep well? When was it last tested?
• What is the fallback water supply arrangement during dry season (February–July)?
• What are the estimated annual water costs including private delivery?

Electricity: Confirm the electrical supply capacity for the property, particularly for large villas with multiple air-conditioning units, pools, and smart home systems. Verify there are no outstanding electricity bills (PEA accounts) that would transfer with the property.

Road access: Confirm the property is accessible by a properly maintained road. Many hillside Koh Samui properties are accessed via private roads across third-party land. Verify that legal road access rights are registered, particularly for rainy-season accessibility.

Sewage and drainage: Confirm how wastewater is managed. Properties without connection to a municipal sewage system require septic tanks that need regular maintenance. Inadequate drainage contributes to both flooding risk and environmental compliance issues.

Internet connectivity: For investment properties intended for short-term rental, fibre internet availability is increasingly a baseline expectation. Verify the available providers and real-world speeds for the specific property location.

13. Obtain an Independent Property Valuation

Never rely solely on the valuation provided by the seller or the selling agent. Their interest in the transaction makes their valuation inherently unreliable. Engage an independent, qualified property valuer with Koh Samui experience before finalising any purchase price.

The three values in Thailand’s property market, as explained by Siam Legal International:

1. Land Department Appraised Value: Calculated by the Treasury Department and updated every four years. Typically significantly below actual market value, particularly in high-demand areas. Used as the base for calculating transfer fees and taxes.
2. Registered Value: The value officially declared at the Land Department for the transfer. Should reflect the true transaction price but is sometimes manipulated downward to reduce tax liability — a practice with serious legal consequences under Section 104 of the Land Code.
3. Market Value: The true price actually paid for the property. An independent valuation from a qualified appraiser is the most reliable indicator of whether you are paying a fair market price.

Why this matters: In some cases, the Land Department appraised value can be a tenth or less of true market value. Understanding all three figures helps you negotiate accurately, budget correctly for transfer taxes, and assess the property’s genuine investment value. See: The True Cost of Buying a Villa in Koh Samui: Taxes, Fees & Hidden Expenses.

14. Review All Contracts with a Bilingual Lawyer

In Thailand, the Thai-language version of any contract is the legally binding document. If there is a discrepancy between the English and Thai versions of a Sales and Purchase Agreement (SPA), the Thai text prevails in court. This makes expert bilingual legal review non-negotiable.

Your lawyer must review and advise on:

• Thai language primacy: Confirm that the Thai text of the SPA accurately reflects all terms negotiated in English. Do not sign any contract without your own independent Thai-language review — not just the developer’s in-house translation.
• Deposit and payment schedule: Review the payment milestones, the conditions under which payments become non-refundable, and the consequences of buyer default or seller default at each stage.
• Completion date and penalty clauses: The contract must specify a clear completion date for off-plan properties, with meaningful penalty clauses enforceable against the developer for late delivery.
• Defect liability period: A defect warranty period (typically one to two years after handover) should be explicitly included, specifying what constitutes a defect, the process for rectification, and the developer’s liability.
• Force majeure clauses: Broadly drafted force majeure provisions can be used by developers to avoid liability for almost any delay. Negotiate specific, narrow definitions.
• Dispute resolution: Confirm the governing law, jurisdiction, and dispute resolution mechanism. Thai courts have jurisdiction over land in Thailand; arbitration clauses may provide a faster alternative in some circumstances.
• Land office documents: At transfer, the Land Department’s own transfer forms are in Thai. Your lawyer must be present at the Land Department on the day of transfer to review and confirm all documents before signing.

15. Verify Tax Obligations and Transfer Cost Allocation

Thailand’s property transfer involves four distinct government charges. Understanding who pays what — and ensuring this is explicitly negotiated and documented in your purchase agreement — prevents expensive last-minute surprises at the Land Department.

The four charges, as detailed by Siam Legal International, are:

SBT vs. Stamp Duty: SBT at 3.3% applies when the seller has owned the property for less than five years. Stamp Duty at 0.5% applies when owned for five years or more, per Siam Legal International. Both are never charged simultaneously. One important exemption: if the seller’s name has appeared in the house registration book (Tabien Baan) for at least one year, SBT is waived regardless of ownership duration.

Key actions:

• Negotiate the transfer cost split explicitly in the SPA. In Koh Samui, it is common for buyer and seller to split the 2% transfer fee equally; all other charges are legally the seller’s responsibility but are frequently negotiated.
• Verify there are no outstanding annual property taxes (Land and Buildings Tax) owed by the seller. Any outstanding tax liabilities transfer with the property.
• Confirm the Land Department appraised value in advance — your lawyer can obtain this from the Land Office before transfer day — so you can budget accurately.
• Avoid under-declaring the transaction price. Under Section 104 of the Land Code, the registration must reflect the true market value. Under-declaration is tax evasion and carries penalties including fines and imprisonment under the Thai Revenue Code.
• For leasehold transfers, the costs are substantially lower: 1% registration fee plus 0.1% stamp duty, calculated on the total lease value.

For a comprehensive breakdown of all purchase-related costs, see: The True Cost of Buying a Villa in Koh Samui: Taxes, Fees & Hidden Expenses.

Red Flags: When to Walk Away

Some warning signs should end negotiations immediately, regardless of how attractive the property or the price appears.

Walk away if:

• No Chanote title. A seller who cannot produce a Chanote (Nor Sor 4 Jor) for a significant investment property — or who offers a Sor Kor 1 or other lesser document — is offering something fundamentally unsecure. Do not let price or location compensate for title risk.
• Seller refuses independent legal representation. Any seller who pressures you to use only their lawyer, or who insists you do not need your own independent counsel, has something to hide. In a legitimate transaction, sellers welcome independent legal scrutiny.
• Pressure to skip or rush due diligence. “The price will be gone tomorrow” or “the other buyer is signing this week” are pressure tactics incompatible with transparent dealing. A legitimate seller understands the due diligence process and allows reasonable time.
• Nominee company structure pressure. If a seller or agent encourages you to hold land through a Thai nominee company — Thai shareholders who hold shares on your behalf as a workaround for foreign land ownership restrictions — reject this approach. Thai authorities now actively investigate such arrangements, and conviction carries criminal prosecution, deportation, and forced asset disposal within 180 days, per Terms.Law.
• Buildings without permits. Any structure that cannot produce its Ror. 4 construction permit — or where the existing structures obviously exceed what the permit describes — is an undisclosed liability. Demolition orders can be issued even after ownership transfer.
• Lease terms beyond 30 years promised as guaranteed. Post the 2025 Thai Supreme Court ruling, any party who promises that pre-agreed “30+30” renewal options are legally guaranteed is either misinformed or misleading you. The initial 30-year lease is valid; beyond that, renewal is not enforceable.
• No FET documentation for condominium purchase. If a developer or seller cannot explain or facilitate the Foreign Exchange Transaction (FET/Tor Tor 3) process for a condominium purchase, the foreign quota legitimacy and Land Department transferability of the unit is in doubt.
• Significant Land Department value discrepancy without explanation. If the seller insists on registering a declared value significantly below the agreed purchase price, they are asking you to participate in tax evasion. This exposes you — not just the seller — to legal liability.
• History of rapid title changes. A property that has changed hands multiple times in quick succession warrants investigation. The title history, visible in the Land Department records, can signal either underlying disputes or speculative price inflation.

Frequently Asked Questions

Q: What is the most important thing to check when buying property in Koh Samui?

A: The title deed type is the foundation of everything else. Insist on a Chanote (Nor Sor 4 Jor) for any significant purchase. A Chanote is the only true freehold ownership document in Thailand, backed by GPS-surveyed boundaries and the national grid. Everything else — building permits, encumbrances, contracts — builds on the title. Without a clean Chanote, no amount of due diligence on other items makes the purchase secure.

Q: Can foreigners own land in Koh Samui outright?

A: Under Thailand’s Land Code Act, foreigners cannot own land in Thailand outright. The two primary legal pathways for foreign buyers are: (1) freehold ownership of a condominium unit within the 49% foreign quota under the Condominium Act B.E. 2522, and (2) a 30-year registered leasehold for houses and villas. Structures (houses, villas) built on leased land can be owned separately by foreigners. For a full explanation, see our guide: Can Foreigners Buy Property in Koh Samui? The Complete Legal Guide.

Q: Are “30+30+30” lease extensions legally valid in Thailand after 2025?

A: No. The Thai Supreme Court ruled in Case No. 4655/2566 (2025) that pre-agreed automatic renewal clauses extending leases beyond 30 years are void and unenforceable. The initial 30-year registered lease remains valid, but any promise of pre-arranged renewal beyond year 30 cannot be enforced in Thai courts, regardless of whether the extension clause was written into the original agreement or whether additional payment was made for the extended term.

Q: How do I verify the foreign ownership quota for a condominium in Koh Samui?

A: Request a written quota confirmation letter from the condominium’s juristic person (management office) showing the current total foreign ownership percentage and the remaining available quota. Your lawyer should independently verify this at the local Land Department. Foreign buyers also need to ensure purchase funds are remitted from overseas in foreign currency to obtain the required Foreign Exchange Transaction Form (FET/Tor Tor 3) for Land Department registration.

Q: Who pays the transfer taxes and fees in a Koh Samui property transaction?

A: Thai law assigns most transfer taxes to the seller (Specific Business Tax or Stamp Duty, and Withholding Tax). The 2% Transfer Fee is typically split 50/50 between buyer and seller, but this is negotiable and must be explicitly agreed in the contract. For a property sold within five years of the seller’s acquisition, Specific Business Tax of 3.3% applies; for properties held longer than five years, Stamp Duty of 0.5% replaces it. Always agree the split in writing before signing any purchase agreement.

Q: How serious is Koh Samui’s water shortage for property buyers?

A: Very serious, particularly for hillside properties and investment villas. Koh Samui experienced a full-blown water crisis in 2023, with the island’s four reservoirs critically depleted and authorities acknowledging severe supply inadequacy. Properties at elevation above 80 metres may receive insufficient pipeline pressure even during normal conditions. Before purchase, verify the property’s water source, the reliability of private well supply, and the cost of private water delivery during dry season. This directly affects operating costs for rental villas and quality of life for residential buyers.

Q: Do I really need an independent lawyer, or can I use the developer’s legal team?

A: You should always engage your own independent, bilingual Thai property lawyer — never rely on the developer’s or seller’s lawyer to protect your interests. The seller’s legal team is instructed by the seller. In Thailand, the Thai-language version of any contract is legally binding; without your own lawyer reviewing the Thai text, you cannot know whether the English version you signed accurately reflects your obligations. For properties in Koh Samui specifically, seek a lawyer with direct Suratthani Land Department experience and verifiable transaction history on the island.

Work with Samui Property Group

The 15-point checklist above is your framework. But due diligence executed without local knowledge, Land Department relationships, and established legal partnerships is still due diligence done at a disadvantage.

Samui Property Group curates a portfolio of villas, condos, and land across every key Koh Samui neighbourhood, paired with the institutional-grade transparency that serious investors require. We work exclusively with independent, bilingual property lawyers. We do not accept instructions from developers that compromise buyer interests. And we flag issues, including title concerns, zoning conflicts, and infrastructure risks, before they become your problem.

Contact Samui Property Group to discuss your investment goals. Whether you are beginning your search or are ready to proceed to due diligence on a specific property, our team is ready to guide you through every step.

This guide is for informational purposes only and does not constitute legal advice. Consult a qualified Thai property lawyer before making any purchase decisions. Laws and regulations are subject to change; verify all information with current primary sources and qualified legal counsel.

Related Guides from Samui Property Group:

• Can Foreigners Buy Property in Koh Samui? The Complete Legal Guide
• How to Buy Property in Koh Samui: Step-by-Step Guide for International Buyers
• Koh Samui Property Ownership Structures Explained: Leasehold, Freehold, and Thai Company
• The True Cost of Buying a Villa in Koh Samui: Taxes, Fees & Hidden Expenses
• Best Areas to Invest in Koh Samui: A Neighborhood-by-Neighborhood Guide