Based on our on-the-ground monitoring, the median price per square metre in off-plan projects on Koh Samui sits at roughly 95,000-130,000 THB/m² in the Bophut and Maenam districts as of 2026. Comparable resale stock in those same locations trades at 120,000-165,000 THB/m². The gap - around 20-25% in the buyer's favour - is real, but it materialises only when the project reaches completion on schedule. Our analysts treat that condition as the central variable in every off-plan assessment.
Payment timelines typically stretch across 18-30 months, which introduces a secondary layer of currency exposure for internationally-based buyers holding non-THB funds. We track each instalment separately in our datasets, because risk exposure compounds with every tranche transferred.
Quick answer
- A typical off-plan project on Koh Samui in 2026 requires 5-7 payment instalments spread across 18-30 months of construction
- The off-plan price discount versus resale stock is approximately 20-25% in Bophut and Maenam, and 15-20% in Lamai and Chaweng
- The reservation fee is usually 100,000-200,000 THB; the contract signing instalment represents 25-35% of the purchase price
- In Thailand there are no third-party payment protection mechanisms for foreign real estate buyers - funds transfer directly to the developer's account
- The primary contractual safeguard is a penalty clause for delays (0.01-0.1% per day of the amount already paid) combined with a termination right
- The highest probability of delays occurs at two points: obtaining the Construction Permit, and the finishing phase
Options and scenarios
Scenario A - pool villa in Bophut, budget 8-12 million THB
Based on our Q1 2026 market monitoring, a typical 2-3 bedroom pool villa in Bophut follows this instalment structure:
- Reservation - 150,000-200,000 THB (roughly 1.5-2% of price), payable immediately, typically non-refundable
- Contract signing (within 30 days of reservation) - 30% of price minus the reservation fee
- Foundation completion - 20% of price
- Structural completion (shell and core) - 20% of price
- Finishing completion - 15% of price
- Handover - 15% of price
For a villa priced at 10 million THB, the buyer will have transferred 50% of total value by the time the foundation is complete. At that stage, the physical asset on the plot consists of a concrete slab and underground utilities. In our risk framework, this is the point of peak exposure relative to tangible collateral.
Scenario B - condominium in Maenam, budget 4-7 million THB
Condominium developers on Koh Samui tend to apply a more gradual payment curve:
- Reservation - 100,000 THB
- Contract signing - 25% of price minus reservation
- 50% construction milestone - 25% of price
- 75% construction milestone - 25% of price
- Handover - 25% of price
Under this structure, when the buyer has paid 50% of the price, the building is already 75% complete. Exposure accumulates more slowly than in Scenario A, which we reflect in a lower risk rating in our comparison.
Scenario C - pre-launch purchase in Lamai or Chaweng
Some developers offer a pre-launch phase at an additional 5-10% discount from the catalogue price but require 35-40% upfront before ground is broken. We have tracked several projects in Lamai with this structure in 2025 and early 2026. The risk profile is the highest of the three scenarios: funds are transferred before construction has started, and the buyer's only leverage is contractual.
Comparison table
| Parameter | Villa Bophut (A) | Condo Maenam (B) | Pre-launch Lamai (C) |
|---|---|---|---|
| Indicative price range | 8-12 million THB | 4-7 million THB | 5-9 million THB |
| Price per m² | 110,000-130,000 THB | 95,000-115,000 THB | 85,000-105,000 THB |
| Discount vs resale | 20-25% | 18-22% | 25-30% |
| Payment before construction starts | 30-32% | 25% | 35-40% |
| Payment by shell-and-core stage | approx. 50% | approx. 50% | approx. 60% |
| Construction timeline | 18-24 months | 20-30 months | 24-36 months |
| Exposure risk level | Medium | Moderate | High |
| Ownership form (foreign buyer) | Leasehold 30+30+30 | Freehold (up to 49% of units) | Depends on structure |
All figures are indicative as of 2026, drawn from our monitoring of developer offerings on Koh Samui.
Risks and mistakes
Stage 1 - before construction (reservation and contract)
Legal status of the project. The developer may not yet hold a valid Construction Permit or, where required, an Environmental Impact Assessment (EIA) report. On Koh Samui, EIA approval is mandatory for projects exceeding 80 units or located near the coastline. In our analysis records, missing EIA approval has delayed construction starts by 6-12 months in documented cases. We also verify that the land title is a Chanote (the highest-grade Thai title deed) and that the plot carries no zoning restrictions.
Direct developer payments. Thailand does not operate any third-party payment protection framework for foreign property buyers. All instalments go directly to the developer's corporate account. The strength of the developer's financial position and the precision of the contract terms are the buyer's primary protection.
What we verify before recommending a developer: track record of completed projects, corporate structure and capitalisation via the Department of Business Development (DBD), and independent legal opinion from a Koh Samui-based lawyer.
Stage 2 - foundation and construction
Monsoon-related delays. Koh Samui's wet season (October-December) consistently slows earthwork and concrete pouring. A realistic weather buffer is 2-3 months beyond the stated timeline.
Material cost pressure. Structural steel prices in Thailand rose approximately 8-12% between 2024 and 2026, per data from the Thai Iron and Steel Industry Club. A developer operating on thin margins may respond by substituting lower-grade materials or pausing construction.
Contract clauses that matter:
- Penalty clause for delays - the market standard is 0.01% per day of the amount already paid, but our analysts have seen this negotiated up to 0.05-0.1% per day in buyer-favourable contracts
- Termination right after a defined overrun period (typically 90-180 days) with a full refund of paid instalments
- Material specification schedule as a numbered annex to the contract - vague language such as 'premium quality finishes' provides no legal basis for a claim
Stage 3 - finishing and handover
Specification drift. In our ground-level monitoring of Koh Samui construction sites, the finishing phase generates the largest number of disputes: material substitutions, floor plan deviations, and items shown in renderings that do not appear in the delivered unit. The contract must name specific manufacturers and product grades for key materials.
Technical inspection (snagging). Before signing the handover certificate, the buyer has the right to inspect the unit. We recommend commissioning an independent technical inspection (typical cost: 15,000-30,000 THB). Professional inspections regularly identify defects not visible to the naked eye - floor drainage gradients, window sealing integrity, and electrical installation parameters.
Common mistakes by first-time international buyers
- Paying a reservation fee before having a Thai lawyer review the contract (legal due diligence cost: 25,000-60,000 THB - a fraction of the transaction value)
- Accepting a contract with no calendar-specific milestone dates; a clause stating 'approximately 24 months' gives no basis for triggering penalty payments
- Omitting land title due diligence, particularly critical in leasehold structures where the underlying ownership chain matters
- Ignoring currency exposure across the 18-30 month payment period; a 10% shift in the THB rate against the buyer's home currency increases total acquisition cost proportionally
FAQ
What is a typical reservation fee for an off-plan property on Koh Samui in 2026?
Reservation fees on Koh Samui generally run 100,000-200,000 THB. The amount is deducted from the first instalment and is typically non-refundable. Some condominium developers in Bophut and Maenam accept lower reservation amounts of around 50,000 THB.
Can a foreign buyer own an off-plan villa on Koh Samui outright?
Foreign nationals cannot hold freehold title to land in Thailand. Off-plan villas are offered either as leasehold (30-year lease with two consecutive renewal options, each for 30 years) or through a Thai-majority company structure. Condominium units can be purchased freehold, provided foreign ownership in the building does not exceed 49% of total floor area.
How large is the off-plan price discount on Koh Samui compared with resale?
Based on our 2026 estimates, the discount ranges from 15-25% depending on the district and the construction stage at the time of purchase. Pre-launch phases carry the highest discount (25-30%) but also the highest risk profile.
What happens if the Koh Samui developer does not complete the project?
Without any third-party payment protection mechanism, recovery of paid instalments depends entirely on the contractual terms and the developer's solvency. A well-drafted contract will include a clause requiring full refund of instalments if the project is not delivered within a specified period. In the worst case, the buyer must pursue a claim through the Thai court system, a process that can take 2-5 years.
What does a standard off-plan payment schedule look like on Koh Samui?
A standard schedule covers 5-7 instalments: reservation (1.5-2%), contract signing (25-35%), foundation complete (15-20%), shell and core complete (15-20%), finishing complete (10-15%), handover (10-15%). The exact split varies by developer and property type.
Does currency exposure affect the economics of an off-plan purchase?
Yes, materially. Payment timelines of 18-30 months create sustained currency exposure. For buyers with non-THB funds, we recommend reviewing hedging options (forward contracts or currency options) for total committed amounts above 1 million THB.
What legal documents should be verified before signing an off-plan contract on Koh Samui?
Our analysts consider the following documents essential: Chanote or Nor Sor 3 Gor land title deed, Construction Permit, EIA report (where applicable), DBD company registration extract for the developer, and condominium licence for apartment projects. A local Thai lawyer should verify all of these before any funds are transferred.
How much does legal due diligence cost for an off-plan purchase on Koh Samui?
Contract review and legal due diligence typically costs 25,000-60,000 THB. Given that this covers verification of the land title, the developer's legal standing, and the contract terms, we consider it one of the highest-return risk-mitigation steps available to the buyer.
When is the most favourable stage to buy off-plan on Koh Samui?
Pre-launch offers the lowest prices but the highest uncertainty. Purchasing after the Construction Permit has been granted and the foundation is in place combines a meaningful discount (15-20%) with confirmation that the project is legally authorised and physically underway. Based on our 2025-2026 observations, that window represents the most balanced risk-to-price ratio across the three scenarios we track.
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