Property Due Diligence in Koh Samui: A Buyer’s Guide

Property due diligence in Koh Samui helps buyers verify ownership, check legal access, review building permissions and understand the obligations attached to a purchase. These checks should take place before you become contractually committed or pay money without clearly agreed protections.

At Doctor Property, we support you throughout your Koh Samui property purchase—from your initial search and viewings to negotiations, document coordination and completion. We work alongside your independent lawyer and other professional advisers, helping you obtain information, raise questions and understand the next steps.

Whether you are buying a completed villa, undeveloped land or an off-plan property, the aim is to establish exactly what you will acquire, identify potential problems and make sure the purchase agreement reflects the findings.

What Is Property Due Diligence?

Property due diligence is an investigation into a property and the proposed transaction. It should confirm the seller’s authority to sell, identify the rights being transferred and uncover obligations or restrictions that could affect the buyer.

An independent Thai lawyer should handle the legal investigation. Depending on the property, a surveyor, engineer or architect may also be needed to assess boundaries, construction or development feasibility.

1. Check the Land Title, Ownership and Boundaries

Your lawyer should examine the title documentation and verify relevant records with the Land Office. A brochure, ownership statement or copy supplied by the seller is a starting point for investigation.

• Confirm the type of title and the rights it provides.
• Verify the registered owner and the seller’s authority to complete the sale.
• Identify registered mortgages, leases, servitudes or other encumbrances.
• Check that the parcel details match the property being offered.
• Establish any additional consents or documents required for completion.

Where boundaries are unclear, arrange an appropriate survey. Fences, walls and boundaries pointed out during a viewing should be checked against the title and survey information.

Key question: are the villa, swimming pool, garden and parking area all within the land or rights included in the purchase?

2. Confirm Legal Road Access

A visible road does not automatically establish a legal right to use it. Some Koh Samui villas are reached through several privately owned land parcels.

Your lawyer should trace the complete route to the public road and verify the legal basis for access across each relevant parcel. This may involve public-road status, road ownership or a registered servitude.

• Who owns and maintains the access road?
• How are maintenance and major repair costs shared?
• Do any restrictions affect use of the road?
• Are the gradient, surface and drainage suitable for everyday access?

For hillside land, consider access for construction vehicles as well as future residents.

3. Review Building Permits and Planning Restrictions

For an existing villa, request the building permit, approved plans and other applicable construction documents. An appropriate professional should assess material differences between the approved plans and the property as built.

Extensions, additional bedrooms, swimming pools and retaining structures may need further investigation. A house registration book should not be treated as proof that all construction has the necessary permissions.

For land purchases, check the feasibility of your intended development before completing the transaction. Planning and environmental requirements can depend on the location and characteristics of the plot, including slope, elevation and proximity to the coast.

Key question: can the property lawfully accommodate your intended construction and use? Nearby buildings do not establish what is permitted on your plot.

4. Understand the Ownership or Leasehold Structure

Foreign ownership of land in Thailand is generally restricted, subject to limited legal exceptions. Foreign buyers should obtain independent advice on the precise rights being offered and the lawfulness of the proposed purchase structure.

A transaction may involve condominium ownership, a registered lease or ownership of a building together with separate rights over the land. Each requires its own checks.

Leasehold Property Checks

• Verify the landowner and the lease’s registration status.
• Confirm the commencement date and remaining term.
• Review transfer, inheritance and termination provisions.
• Establish who owns the building during and after the lease.
• Have renewal promises assessed separately from currently registered rights.

A marketed total term should be supported by a clear explanation of what is registered now and what depends on future action.

Company-Related Transactions

If a company is involved, establish whether you are acquiring property, shares or another interest. Your advisers may need to investigate the company’s ownership, accounts, taxes, debts and other liabilities, as well as the legality of the arrangement.

Ask for a written explanation of the rights you will acquire and any restrictions affecting their future transfer.

5. Arrange a Building Inspection and Check Utilities

Legal due diligence does not establish a villa’s physical condition. An independent building inspection can identify defects, likely repair costs and matters requiring specialist investigation.

• Structural movement and retaining walls.
• Roof condition, waterproofing and water ingress.
• Site drainage and stormwater management.
• Electrical installations, plumbing and wastewater systems.
• Swimming-pool equipment and other major installations.

Drainage and retaining structures deserve particular attention on hillside sites.

Water, Electricity and Shared Infrastructure

Establish how utilities are supplied, metered and billed. Request recent bills and agreements covering private water systems, electricity distribution, pumps or shared equipment.

Within a development, review common-area charges, management agreements and responsibility for major repairs. Ask about outstanding charges and planned works that could affect future costs.

6. Carry Out Additional Checks for Off-Plan Property

Buying off-plan property in Koh Samui requires investigation of both the property rights and the developer’s obligations to deliver the finished home.

Check the developer’s control of the land, relevant permissions, contracting company and completed projects. The agreement should address:

• The plot, floor plans and construction specifications.
• Items included in the price and procedures for approving changes.
• Payment milestones and independent verification of progress.
• Completion deadlines and remedies for delay or non-completion.
• Delivery of roads, utilities and shared facilities.
• Inspection, snagging, handover and defect obligations.

If rental returns are promoted, examine the supporting agreement, conditions, costs and party responsible for payment. Financial projections should be assessed separately from enforceable contractual obligations.

7. Review the Deposit and Purchase Agreement

The purchase agreement should reflect the due diligence findings. Your lawyer should review the purchase conditions, payment schedule, allocation of taxes and fees, completion requirements and consequences of default.

Address existing tenants, rental bookings, management contracts and other commitments that could continue after completion.

For furnished villas, attach an agreed inventory covering furniture, appliances and important equipment. Clearly identify excluded items.

Where a problem must be resolved before completion, specify the required action, supporting evidence and deadline. Arrange any necessary final checks before releasing the remaining funds.

Koh Samui Property Due Diligence: Document Checklist

Ask the seller or agent for the following documents where applicable. Your lawyer should confirm what is required for the particular transaction.

• Land title documentation, including registered entries.
• Seller identification and authority to sell.
• Access-road documents and relevant registered rights.
• Building permits and approved plans.
• Existing leases, tenancies and management agreements.
• Recent utility bills and shared-infrastructure agreements.
• Common-area charges and outstanding-payment information.
• Reservation terms, draft purchase agreement and inventory.
• For off-plan purchases, specifications, payment milestones and delivery obligations.

What Happens If Due Diligence Finds a Problem?

Some issues can be resolved through additional documents, corrective work or amendments to the agreement. Others may affect the property’s value, intended use or suitability.

Ask your advisers to explain the practical consequences, available solutions and unresolved risks. Distinguish between a correction that has been completed and a promise to address the issue later.

Frequently Asked Questions

When should property due diligence begin?

Involve your lawyer before signing reservation terms or paying a deposit. The agreement should provide an appropriate investigation period and clearly explain the conditions for proceeding or receiving a refund.

Who should conduct due diligence in Koh Samui?

An independent Thai lawyer representing the buyer should handle legal checks. Surveyors, engineers or architects can investigate technical matters relevant to the property.

Does a land title confirm that a villa has legal road access?

Access requires its own investigation. Your lawyer should check the full route to the public road and verify the rights covering each relevant section.

Is a building inspection included in legal due diligence?

Do not assume it is included. Confirm the scope of your lawyer’s work and commission a separate technical inspection where appropriate.

How long does property due diligence take?

The timeframe depends on the transaction, document availability and issues requiring further investigation. Agree a realistic schedule with your lawyer and reflect it in the reservation or purchase terms.

Doctor Property Supports You Throughout Your Purchase

From finding the right property and arranging viewings to negotiations, document coordination and completion, Doctor Property is with you throughout the buying process.

We help obtain available property information, raise questions with sellers and coordinate communication with your independent lawyer and other advisers, so you can make informed decisions at each stage.

Planning to buy property in Koh Samui? Contact Doctor Property to discuss your requirements and the available documentation for properties on your shortlist.

This article provides general information. Requirements depend on the property, the parties and the transaction. Obtain independent Thai legal advice before signing an agreement or transferring funds.