Property Due Diligence in Thailand

Checks, costs & money

The checks your lawyer should carry out before you sign anything binding, for land, villas, condos and off-plan projects on Koh Samui, and the red flags that should stop a purchase.

By Samui Real Estate, Property ConsultantLast reviewed November 20268 min read

Due diligence is the single most effective way to protect your money when buying on Koh Samui. It is where problems are found: a title that isn’t what it seems, a road that isn’t legally yours to use, a house built without permits, a seller who can’t sell. This guide sets out what a thorough check covers, by property type, so you know what to expect from your lawyer and what to ask if something is missing. For the overall process, see buying property in Koh Samui.

General information, not legal advice. Due diligence must be carried out by an independent property lawyer acting only for you.

When due diligence happens

1. You reserve the property. A reservation agreement takes the property off the market for an agreed period, in return for a deposit.
2. Your lawyer runs the checks, usually within one to three weeks.
3. You receive a written report, setting out what was checked, what was found and what is recommended.
4. You sign the sale and purchase agreement, renegotiate, or withdraw.

The reservation agreement should say clearly that the deposit is refundable if due diligence reveals a material problem. If a seller won’t agree to that, ask why.

1. The title deed

Everything starts with the title deed. Your lawyer should obtain a copy of the front and back and check it against the original at the Koh Samui Land Office.

Title	What it is	Our view
Chanote (Nor Sor 4 Jor)	Full ownership title, GPS-surveyed boundaries	Preferred
Nor Sor 3 Gor	Confirmed right of use, surveyed from aerial maps; transferable	Acceptable with extra checks; often upgradeable
Nor Sor 3	Right of use with less precise boundaries; sale requires a 30-day public notice	Higher risk
Sor Kor 1 / Por Bor Tor 5	Possession claims or tax receipts, not titles	Avoid
Sor Por Kor 4-01	Agricultural reform land: can’t be sold, only inherited	Avoid

What your lawyer checks on the title:

• The registered owner matches the seller, and their ID.
• Plot size and location match what you’ve been shown.
• The back of the deed: every registered transaction, including leases, mortgages, usufructs, superficies, servitudes and seizures.
• The title history, to spot recent upgrades or disputed transfers.

2. Encumbrances and disputes

Beyond the title deed, a thorough search covers:

• Mortgages that must be discharged at transfer.
• Existing leases or rights, which may conflict with what you are buying.
• Court cases or seizure orders against the seller or the land. A search of the Legal Execution Department can show whether the seller is bankrupt or the land is attached.
• Boundary disputes with neighbours.

3. Legal access and utilities

On a hilly island, access is one of the most common problems.

• Road frontage onto a public road, or
• A registered servitude over the land the access road crosses. An informal road “everyone uses” is not enough.
• Electricity and water: where they come from, whether connections exist or must be paid for, and whether pipes and lines cross other plots (they should be covered by a servitude).

See usufruct, superficies and servitudes for how access rights work.

4. Planning, zoning and building rules

• Town planning zone: what can be built on the plot, and how much of it can be covered.
• Slope and height rules: Koh Samui restricts building on steep slopes and at higher elevations, and limits building height, particularly near the coast.
• Coastal set-back: extra limits on building close to the shoreline.
• Environmental Impact Assessment (EIA): required for larger projects, such as condos above a certain size and hotels above a certain number of rooms.

These rules are set by local regulations that are updated from time to time, so the check should be done against the rules in force for that plot.

5. Buildings and permits

For any existing building:

• The building permit, and that what was built matches the approved plans.
• The completion certificate where one is required.
• House registration (Tabien Baan) for the house, and whether it is in the seller’s name.
• Unapproved extensions or structures, which can cause problems on resale or with insurance.
• A physical survey by a building inspector: structure, roof, waterproofing, pool, drainage and electrics.

6. The seller

• Individual sellers: identity, marital status, and spouse consent where the property is marital property. A sale without a required spouse’s consent can be challenged.
• Company sellers: company registration documents, current directors and their signing authority, and the shareholder resolution approving the sale.
• Estate sales: probate or court order appointing the administrator.
• Leasehold sellers: whether the lease allows assignment, and the landowner’s consent if it’s needed.

Condo checks

• The building is a registered condominium, and the unit has its own Or Chor 2 title.
• The juristic person confirms foreign quota is available for this unit.
• A debt-free letter confirms there are no unpaid common-area fees.
• The latest accounts, budget and sinking fund balance are reasonable.
• The house rules, especially on short-term letting and pets.
• Any planned special levies or major repairs.

See buying a condominium in Thailand.

Off-plan and developer checks

For a project not yet built, the checks shift from the property to the developer:

• Company registration, paid-up capital, directors and any history of disputes.
• Track record: completed projects, delivered on time and to specification. Visit one if you can.
• The land: who owns it, whether it’s mortgaged to fund the build, and on what terms.
• Permits: building permit issued, EIA approved where required.
• The contract: specification, completion date, penalties for delay, what happens if the project stops, and how your payments are held.
• Rental guarantees: who pays, from what, and whether it’s in the contract.

See buying off-plan property.

Leasehold villas: checking the lease chain

When you buy an existing leasehold villa, you are usually taking over someone else’s lease. Extra checks apply:

• The remaining term. A lease registered 12 years ago has 18 years left, whatever the original brochure said.
• The original landowner and whether the land has since been sold or inherited. Renewal promises may not bind the new owner.
• Assignment rights. Whether the lease can pass to you without the landowner’s consent, and if consent is needed, that it is given in writing and registered.
• The superficies and the house. Both should transfer to you at the Land Office, not just the lease.
• Any sublease between the seller and someone else, which would mean you aren’t dealing with the registered tenant.

Villa estates and plot sales

Many Samui developments sell villas or plots on a larger piece of land. Check:

• Subdivision. Each plot should have its own title deed, or the project should hold a land allocation permit where the law requires one. Selling many plots from one title without the proper permit is a common source of later problems.
• Common areas. Who owns the roads, pool and gardens, and how they are maintained and paid for.
• Estate rules and fees, and whether they are registered or just contractual.

Samui-specific physical checks

• Slope and retaining walls. Hillside plots need sound engineering; ask for the engineer’s drawings.
• Water. Many areas rely on wells or delivered water, particularly in the dry season. Check the supply and any well permit.
• Power capacity. Large villas with several air-conditioning units may need a higher supply from the Provincial Electricity Authority.
• Coastal erosion and flooding on beachfront and low-lying plots. Visit after heavy rain if you can.
• Mobile signal and internet, which still vary between hillsides.

What a good due diligence report includes

• A summary: proceed, proceed with conditions, or don’t proceed.
• Copies of the title deed (front and back) and every document reviewed.
• Each risk found, how serious it is, and how to deal with it.
• The structure recommended and the documents needed.
• The fees and taxes expected at transfer, and who pays each one.

Red flags that should stop a purchase

What due diligence costs, and how long it takes

Due diligence is normally part of your lawyer’s fee for the purchase. Ask for a fixed written quote that covers the checks, the report, the contract review and the transfer. A straightforward condo can be checked in about a week; land or a villa with permits to review often takes two to three weeks.

Frequently asked questions

General information only, not legal advice. Have every purchase checked by an independent lawyer.