Based on our on-the-ground monitoring, off-plan residential prices on Koh Samui in 2026 sit roughly 15-25% below comparable resale properties in the same districts. Our price tracking puts off-plan villa stock in Bophut at approximately 75,000-95,000 THB per sq m, while finished villas in the same area start from 100,000-120,000 THB per sq m (Q1 2026 data). That spread is the core arithmetic behind investor appetite for pre-construction purchases on the island.
In our Koh Samui data sets we currently track more than 40 active off-plan projects, with roughly 60% concentrated in three districts: Bophut, Maenam, and Chaweng Noi. A staggered payment schedule spread across 18-30 months of construction means buyers finance in tranches, but they also absorb completion risk at every stage. Below we break down the mechanics in detail.
Quick answer
- The off-plan discount on Koh Samui as of 2026 sits at approximately 15-25% relative to resale prices in the same district
- A typical payment schedule runs 5-7 tranches over 18-30 months of construction
- Reservation deposits are generally 100,000-300,000 THB and are almost always non-refundable
- There are no escrow-style payment protection mechanisms available to foreign buyers in Thailand; contractual clauses and the developer's financial health are the sole safeguards
- Key protective clauses include late-completion penalties (0.01-0.1% per day), a right of termination after a defined overrun period, and a structural warranty (typically 1-5 years)
- Based on our market estimates, 8-12% of off-plan projects on Koh Samui experience delays exceeding six months
Options and scenarios
What a typical off-plan payment schedule looks like on Koh Samui
We track construction progress across the island and have reviewed contracts from several dozen developers. The schedule below reflects an averaged framework for villa projects in Bophut and Maenam.
Stage 1 - Reservation. A deposit of 100,000-300,000 THB paid on expression of interest (day zero). This amount is almost universally non-refundable. Absolute exposure is modest at this point, but recovery probability on this specific sum is effectively zero if the buyer withdraws.
Stage 2 - Contract signing. A payment of 25-35% of the purchase price (net of the reservation deposit), due 14-30 days after reservation. From this moment the buyer has committed material capital, and construction has often not yet broken ground. Contract quality is therefore most critical at precisely this stage.
Stage 3 - Foundation and structure. A further 20-30% due upon confirmed completion of foundations or structural frame, typically 3-8 months after contract signing. At this stage we verify whether the developer holds a valid construction permit (Por. Or. 4) and, where required, an Environmental Impact Assessment (EIA) clearance.
Stage 4 - Roof and enclosure. A payment of 15-20% once the building envelope is closed, usually 8-14 months in. Delay risk at this stage is driven primarily by weather: Koh Samui's monsoon season (roughly November through January) can halt work on eastern-facing sites for four to eight weeks at a time.
Stage 5 - Fit-out and installations. A payment of 10-15% on completion of interior finishing, typically 14-22 months into the schedule. Issues at this stage tend to involve workmanship quality rather than pure timing.
Stage 6 - Handover and title transfer. The final 5-15% is paid at Land Office registration, normally 18-30 months after contract signing. Transfer tax and registration fees add approximately 1.5-3.5% of property value on top of this final payment.
The mathematics of risk exposure over time
For a villa priced at 10 million THB in Maenam on a 24-month schedule, cumulative buyer exposure looks roughly as follows: after month one, approximately 30-35% of the total value is committed; by month eight, 50-65%; by month fourteen, 65-85%. The steepest risk jump therefore occurs at the very start, between reservation and contract signing, not midway through construction.
Off-plan discount versus resale: district-level figures
In Bophut (near Fisherman's Village), off-plan villas of 150-200 sq m are currently priced in the 8-14 million THB range, while comparable completed properties reach 11-18 million THB. In Maenam the discount is somewhat wider - per our estimates, closer to 20-25% - reflecting a larger land supply in that corridor.
In Lamai, where new project supply is thinner, the off-plan discount compresses to 10-15%, making the pre-construction proposition less compelling on price alone, though the lower developer competition can mean fewer execution risks.
For comparison, in Phuket's Bang Tao and Layan districts the off-plan discount in 2026 runs at approximately 18-30%, against a meaningfully larger project count and higher absolute price levels.
Comparison table
| Parameter | Bophut (Koh Samui) | Maenam (Koh Samui) | Lamai (Koh Samui) | Bang Tao (Phuket) |
|---|---|---|---|---|
| Off-plan price per sq m (THB) | 75,000-95,000 | 65,000-85,000 | 80,000-100,000 | 95,000-140,000 |
| Resale price per sq m (THB) | 100,000-120,000 | 85,000-110,000 | 95,000-115,000 | 130,000-180,000 |
| Estimated off-plan discount | 15-22% | 20-25% | 10-15% | 18-30% |
| Typical build period | 18-24 months | 18-24 months | 18-24 months | 18-30 months |
| Active off-plan projects (2026) | approx. 15 | approx. 12 | approx. 6 | 50+ |
| Deposit at contract signing (% of price) | 25-35% | 25-35% | 30-40% | 25-40% |
| Estimated gross rental yield (annual) | 5-7% | 5-8% | 4-6% | 5-8% |
All figures are indicative, based on Tajlandia.com team market monitoring as of Q1 2026.
Risks and mistakes
No structural payment protection mechanism
This is the most significant structural gap in Thai off-plan purchases: payments go directly to the developer. There is no payment protection arrangement available to foreign buyers in Thailand. In practice, the only safeguards are contractual provisions and the developer's financial capacity to complete the project. Our standard due-diligence process covers the developer's track record of completed projects, the ownership structure of the development company, and whether the underlying land is free of mortgage encumbrances.
What actually causes construction delays
EIA and permits. Projects in Koh Samui's coastal zones require an Environmental Impact Assessment. In our experience, obtaining EIA clearance routinely runs 3-6 months longer than developers declare upfront. We look for contract language that ties construction commencement to permit issuance, not to a fixed calendar date.
Structural phase. The monsoon season (November through January) on Koh Samui's eastern coast - Chaweng and Lamai in particular - causes regular work stoppages of four to eight weeks. Experienced island-based developers factor this into their schedules; newer entrants frequently do not.
Fit-out phase. All materials brought to the island travel by ferry from Surat Thani, which creates logistical bottlenecks that have no equivalent in Phuket, where supply chains are considerably better developed.
Technical handover. We verify whether the contract provides for an independent snagging inspection before the buyer signs any handover certificate. Without this right, defect claims become significantly harder to enforce.
Key contractual clauses to negotiate
- Late-completion penalties (liquidated damages): the market standard is 0.01-0.05% of property value per day of overrun. A small number of contracts offer 0.1% - rare, but worth pushing for in negotiation
- Right of termination with full refund: look for a clause allowing the buyer to exit with 100% of payments returned if the delay exceeds 180-365 days
- Structural warranty: the market norm is 1-2 years on finishing elements and 5 years on the structure. Some developers offer only 12 months in total
- Materials specification: the contract should include a detailed specification schedule as an annex. Substitution of materials for cheaper alternatives without buyer consent is a recurring issue in the market
Common errors made by first-time buyers
Skipping land title verification. Some plots on Koh Samui carry only a Nor Sor 3 Gor title rather than a full Chanote. The difference is fundamental to the security of any property investment.
Ignoring transfer costs. Transfer fee, stamp duty, and withholding tax together add up to roughly 1.5-3.5% of assessed value. Developers sometimes offer a 50/50 cost-share arrangement, but this must be written into the purchase agreement to be enforceable.
Ignoring currency risk on a multi-year payment schedule. Over 24 months, the THB exchange rate against major currencies can shift by 5-15%. Payments denominated in THB mean the buyer carries full foreign-exchange exposure throughout the build period.
FAQ
Is buying off-plan on Koh Samui a safe option for foreign buyers?
Safety depends on three factors: the developer's track record (how many projects delivered on schedule), the quality of contract provisions (penalties, termination rights, materials specification), and the land title (Chanote as a minimum requirement). There is no payment protection mechanism of the escrow type available to foreign buyers in Thailand.
What is the reservation deposit for an off-plan property on Koh Samui in 2026?
Typically 100,000-300,000 THB. In the vast majority of cases this amount is non-refundable and is credited toward the purchase price at contract signing.
How large is the off-plan price discount compared with the resale market?
Based on our Q1 2026 data, the discount across Koh Samui ranges from 10-25% depending on district. The widest gap is in Maenam (20-25%); the narrowest is in Lamai (10-15%).
How long does it take to build an off-plan villa on Koh Samui?
The standard schedule is 18-24 months from contract signing. In our project tracking, we observe delays of 2-6 months in approximately 8-12% of projects. The monsoon season (November through January) is the primary driver of seasonal stoppages.
Can I resell an off-plan unit before handover?
Most developer contracts on Koh Samui permit assignment of contractual rights to a third party. The assignment fee is typically 1-3% of contract value. We always check whether the contract contains any prohibition on assignment before advising on this option.
What taxes are due at off-plan property transfer?
At Land Office registration the applicable charges are: transfer fee (2% of assessed value), stamp duty (0.5%) or specific business tax (3.3%, whichever applies), and potentially withholding tax. The combined cost runs to approximately 1.5-3.5% of property value.
In which currency are off-plan payments made?
Payments are denominated in THB. Inbound international transfers must be received into a Thai bank account and documented with a Foreign Exchange Transaction Form (FETF), which Land Office registration requires as proof of foreign-sourced funds.
Can a developer change the materials specification mid-build?
Without an explicit contractual restriction, yes. We look for a detailed materials schedule annexed to the contract and a clause prohibiting substitution without the buyer's written consent.
Which Koh Samui districts offer the strongest capital appreciation potential for off-plan buyers?
Based on the data we aggregate, Maenam offers the most favourable price-to-upside ratio, driven by ongoing infrastructure development in the north of the island. Bophut retains its premium positioning and delivers more stable, if percentage-wise more modest, value appreciation.
Researching property in Phuket or Koh Samui? Get in touch - our analysts will prepare a data brief for your shortlisted location.