In Q1 2026, our analysts track the average price of a new off-plan villa in Bophut and Maenam at roughly 95,000 - 130,000 THB per sq m. Against comparable secondary-market stock in the same districts, that represents a discount of 15-25% - based on transaction data we have been monitoring since 2023. The off-plan discount remains the primary economic argument for early-stage entry, but it demands a precise risk assessment at every construction milestone.
Our team conducts on-the-ground site checks on Koh Samui every quarter. In our 2025 data sets we logged 12 active off-plan villa projects in the above-5-million-THB segment with planned completion in 2026-2027. Delays of 3-6 months affected roughly 30% of those projects, concentrated in the finishing phase.
Quick answer
- Off-plan discount on Koh Samui in 2026 sits at approximately 15-25% relative to completed villas in Bophut, Maenam and Lamai
- Typical payment schedules spread across 4-6 tranches tied to construction milestones; the reservation deposit is usually 50,000 - 200,000 THB
- Buyer financial exposure builds gradually - once 50% has been paid (typically at roof-completion stage), the position is already material
- Thailand has no escrow or trust-account system protecting off-plan payments for foreign buyers; contractual clauses and developer track record are the only safeguards
- Average villa construction time on Koh Samui runs 14-22 months from contract signing
- Key contract provisions to verify: daily penalty clause for delays, termination right after a defined overrun period, and a structural warranty
Options and scenarios
Scenario 1 - early-stage entry (reservation or foundation phase)
The buyer enters with minimal financial exposure. The reservation deposit is typically 50,000 - 200,000 THB. Within 30 days the formal sale and purchase agreement is signed, requiring a further 25-30% of the purchase price. Combined exposure at this point is roughly 30% of total value. The developer is still breaking ground and finalising permits. Time-risk is highest here (longest wait to handover), while financial risk remains relatively contained.
In Maenam and Bophut we monitor projects where foundation-phase pricing started at 85,000 THB per sq m. Comparable completed villas in those districts trade at 110,000 - 140,000 THB per sq m on the secondary market, per our estimates.
Scenario 2 - entry at structural-completion stage
The buyer joins once the building frame is visible. The discount against final delivery price narrows to roughly 8-15%. Entry exposure is higher (earlier tranches must be settled at signing), but the wait shrinks to 6-10 months. Structural risk - foundation quality, compliance with plans - can be partially verified by visual inspection.
Scenario 3 - completed property (secondary market)
No discount applies; the buyer pays full market value but carries zero construction risk. A full technical inspection is possible before commitment. In Lamai, a completed 200-sq-m villa with a pool is priced at approximately 12-16 million THB as of 2026. An equivalent off-plan project in Maenam at reservation stage would be quoted at 9.5-13 million THB.
Comparison table
| Parameter | Off-plan (early stage) | Off-plan (structural stage) | Secondary market (completed) |
|---|---|---|---|
| Discount vs market price | 15-25% | 8-15% | 0% (base price) |
| Typical entry exposure | 25-30% of price | 40-55% of price | 100% of price |
| Time to handover | 14-22 months | 6-10 months | Immediate |
| Delay risk | High | Moderate | None |
| Developer insolvency risk | Highest | Moderate | None |
| Quality verification possible | Plans only | Partial | Full inspection |
| Indicative price (Bophut, 200 sq m) | 9.5-11 million THB | 11-13 million THB | 13-16 million THB |
| Approximate USD equivalent | 265,000 - 306,000 | 306,000 - 362,000 | 362,000 - 445,000 |
Typical off-plan payment schedule on Koh Samui
The tranche structure below is drawn from contracts we analysed in 2025 and 2026 across projects in Bophut, Maenam, Lamai and Chaweng.
- Reservation deposit - 50,000 - 200,000 THB (fixed sum, not a percentage). Credited against the first tranche. Usually non-refundable after the cooling-off window (7-14 days)
- Contract signing (30 days after reservation) - 25-30% of purchase price. This is the point of formal contractual commitment
- Foundation completion - 15-25% of price. Developer typically provides a photo report or invites an on-site inspection
- Structural completion (roof completion) - 15-25% of price. Cumulative buyer exposure reaches 55-80% of total value at this stage
- Interior finishing - 10-15% of price (not universal; some developers merge this tranche with handover)
- Key handover (transfer) - 10-20% of price. Final payment, after which title is registered at the Land Office
The exposure arithmetic is straightforward: after the third tranche (foundation completion) the buyer has committed 40-55% of the property value. Withdrawing at that point means losing a material portion of paid funds unless the contract includes a refund clause for developer default.
Risks and mistakes
Permitting risk at foundation stage and EIA requirements
Since 2024, local authorities on Koh Samui have tightened Environmental Impact Assessment (EIA) requirements for projects on slopes exceeding 35 degrees. We have tracked cases where developers launched off-plan sales before all permits were in place, introducing delays of 3-12 months before a single wall was built. Buyers should verify the construction permit number before signing any agreement.
Monsoon-season slowdowns at structural stage
Construction activity on the island slows materially during the monsoon season (October through December). In our 2025 data, delays at the structural phase averaged 4-8 weeks per project. The contract should carry a daily penalty clause of 0.01-0.05% of paid tranches for each day of overrun beyond the agreed completion date.
Finishing-stage substitution risk
This is the most common dispute point. Flooring, kitchen and bathroom fittings, pool specification - every item should be listed in a material specification annex attached to the contract. Our analysts have documented cases where developers substituted cheaper materials without buyer approval. We recommend a clause explicitly prohibiting substitution without written consent.
Developer non-completion risk
Thailand has no statutory fund or trust-account mechanism protecting off-plan payments for foreign buyers. Funds go directly to the developer's bank account. The practical safeguards available are:
- A verified track record (completed projects, market presence of more than five years)
- Clear land title held by the developer (freehold, not leasehold-only)
- A contractual clause entitling the buyer to a full refund of paid tranches if completion is delayed beyond a defined longstop date (for example, 12 months after the planned handover date)
- A completion guarantee from a third party - offered by some premium developers but not a market standard
Common mistakes made by international buyers
- Paying a reservation deposit before verifying the construction permit
- Accepting a contract with no daily penalty clause for delays
- Overlooking transfer costs at the Land Office (2% transfer fee plus 0.5% stamp duty, rising to approximately 6.3% total when Specific Business Tax applies on resales within five years of purchase)
- Converting purchase sums at spot rates without budgeting for bank spread (real cost of a THB wire transfer is typically 1.5-3% above the mid-market rate)
- Skipping independent legal review; the developer's lawyer represents the developer, not the buyer
Discount arithmetic - a worked example from Bophut
Consider a 200-sq-m villa with a pool in Bophut. Figures are indicative, based on 2026 market data:
- Off-plan price at reservation stage: 10.5 million THB (approx. 292,000 USD at 36 THB/USD)
- Equivalent completed villa on secondary market: 13.5 million THB (approx. 375,000 USD)
- Nominal discount: 3 million THB (approx. 83,000 USD) - representing 22%
- Cost of capital locked in for 18 months (at 5% per annum): approx. 22,000 USD
- Real discount after cost of capital: approx. 61,000 USD, equivalent to roughly 16-17%
That real discount is the effective compensation for construction risk, currency risk and illiquidity. Currency movement alone is significant: over the 12 months from Q2 2025 to Q1 2026, the THB/USD rate fluctuated across a range that could shift the USD cost of the investment by roughly 5-6% in either direction, based on our tracking.
Phuket comparison
For context, our analysts compare off-plan Koh Samui with equivalent product in Phuket. In Bang Tao and Layan, off-plan villas of comparable specification are priced at approximately 120,000 - 170,000 THB per sq m as of 2026 - roughly 25-35% above Koh Samui levels. However, the off-plan discount against Phuket secondary-market prices is narrower (approximately 10-18%), because investor demand is stronger and developers have less incentive to discount early-stage pricing aggressively.
On Koh Samui we monitor fewer active projects overall, but larger discounts and longer build cycles. On the rental yield side, average occupancy for premium villas on Koh Samui in 2025 was, per our estimates, 58-65% over the November-April high season, compared with 65-75% for comparable stock in Bang Tao, Surin and Kamala on Phuket.
The summary from our analysis desk: off-plan entry on Koh Samui in 2026 offers a real discount of approximately 15-25%, but it requires thorough developer due diligence, detailed contract review and an acceptance that paid tranches carry no institutional protection. We recommend engaging independent legal counsel before signing and scheduling regular on-site construction checks throughout the build cycle.
FAQ
What off-plan discount can buyers realistically expect on Koh Samui in 2026?
Based on our estimates, the discount in Bophut and Maenam is approximately 15-25% against comparable completed villas. In Lamai and Chaweng the gap is smaller - around 10-18% - because supply of new projects is thinner there.
Are off-plan payments on Koh Samui protected by any trust or escrow mechanism?
No. Thailand has no statutory escrow or trust-account system for foreign off-plan buyers. Payments go directly to the developer. Protection comes solely from contractual terms and the developer's verified track record.
What penalty clause for delays should a Koh Samui off-plan contract include?
The market norm is a daily penalty of 0.01-0.05% of paid tranches for each day of overrun. Some developers also include a termination right with full refund of paid amounts if the delay exceeds 6-12 months.
How long does it take to build an off-plan villa on Koh Samui?
Typically 14-22 months from contract signing for a 150-300 sq m villa. Based on our 2025 site monitoring, the average actual delay was approximately 3 months beyond the contractual date.
What are the total transaction costs when buying off-plan from a developer?
The buyer typically covers a 2% transfer fee and, where applicable, 0.5% stamp duty at the Land Office. Market practice on Koh Samui often splits these costs equally between buyer and developer, but this is negotiable and must be specified in the contract.
How should funds be transferred from abroad to pay for an off-plan purchase?
Funds should be wired from a personal bank account directly to the developer's Thai bank account. The receiving Thai bank issues a Foreign Exchange Transaction Form (FETF), which is required to register title at the Land Office. Transfers routed through intermediaries or converted via cryptocurrency do not generate a FETF and will block the title registration.
Which districts on Koh Samui have the most off-plan supply in 2026?
According to our data, the largest concentration of active off-plan projects is in Bophut (around Fisherman's Village and the Big Buddha hillside) and Maenam (north coast). Lamai is developing more slowly but we have tracked an increase in new project launches there since mid-2025.
How does Koh Samui off-plan compare with Phuket in terms of price and yield?
Off-plan villas in Bang Tao and Layan on Phuket are priced roughly 25-35% higher per sq m than comparable Koh Samui product. The discount against completed stock is narrower on Phuket (10-18%), and rental occupancy is higher (65-75% vs 58-65% in peak season, per our estimates). Koh Samui offers a larger headline discount and lower entry cost; Phuket offers stronger liquidity and rental consistency.
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