Security Deposit Rules on Koh Samui: What Renters Need to Know (2026)

Ask five people on Koh Samui how much security deposit is normal, and you'll likely get five different answers — because there is no single legal deposit amount in Thailand, only market habit and, since September 2025, a specific rule that applies to some landlords but not others. This guide sets out what a deposit typically costs on the island, which rules actually apply to your situation, what a landlord can legally deduct, and what to do if the deposit isn't returned.

How much deposit is normal on Koh Samui

There is no official statistic for deposit amounts on the island — every figure quoted online, including the ones below, comes from property listings and agents rather than a government register. Based on current listings and our local team's ongoing contact with the rental market, deposits on Koh Samui typically run from one to three months' rent, most often paid alongside one month's rent in advance. Where you land in that range depends mostly on the property type, the individual landlord, and how competitive the market is at the time you're negotiating — see our guide to long-term rental prices by property type and area for what the rent itself typically costs.

Two different sets of rules, depending on your landlord

Since 4 September 2025, Thailand has had a consumer-protection notification from the Office of the Consumer Protection Board (OCPB) that sets firm limits for landlords who operate residential rentals as a business — most legal summaries describe this as applying from three or more rented units upward. Outside that category, deposits sit under the general Civil and Commercial Code and whatever your written contract says. We cover this split in full in our guide to Thailand's 2025/2026 rental law; here is what it means specifically for your deposit.

If your landlord rents out three or more units

• Deposit plus any advance rent, combined, cannot exceed three months' rent.
• If there is no damage, the deposit must be refunded immediately when the lease ends.
• If the landlord needs to inspect the unit first, the refund is due within 7 days.
• If deductions are made for damage or unpaid charges, the remaining balance is due within 14 days.
• Deductions for ordinary wear and tear are not allowed.

If your landlord is a private individual with one or two units

This describes most individual condo owners and many house and villa owners on Koh Samui. For this group, none of the limits above apply as a matter of law: there is no statutory cap on the deposit and no statutory deadline for returning it. Your written contract is the only thing governing these questions, so read the deposit clause carefully before signing rather than assuming the OCPB protections above will apply to you.

One honest caveat is worth flagging here: court rulings on this point show that whether a small landlord counts as running a rental "business" can depend on the specifics of the case — how the property is marketed and managed — not just a simple headcount of units. If your landlord's situation looks borderline, it's reasonable to ask them directly which rules they consider themselves under, or to check with the OCPB hotline before you sign.

Commercial landlord vs. private landlord, at a glance

What a landlord can and can't deduct

Regardless of which category your landlord falls into, the same common-sense principle applies in practice: a deposit is meant to cover actual damage or unpaid amounts, not the normal effects of someone living in a home for a year. Cleaning and air-conditioning servicing are the two deductions that cause the most disagreement on Koh Samui. A charge for either is on solid ground when it is written into the contract in advance, or when it clearly goes beyond what normal use would cause — a heavily soiled unit, or an aircon unit that was never serviced during a long tenancy. A standard end-of-tenancy clean or a routine filter service, on the other hand, is closer to normal wear and tear and is the kind of deduction worth pushing back on, especially if your landlord counts as a business under the 2025 rule.

Genuine damage — a broken appliance, damaged furniture, holes in a wall beyond a picture hook — is deductible either way, but the amount should reflect the actual cost of repair, not a guess, and the landlord should be able to show a receipt or a reasonable quote on request.

Handover photos: not always compulsory, always worth doing

Sources disagree on exactly how far the 2025 rule goes: some describe a documented handover record as a legal requirement for business landlords, while a closer reading of the OCPB's own sample contract suggests it is encouraged rather than mandated as a separate signed document. Given that uncertainty, treat a photographed handover as something you do regardless of what your landlord is legally required to provide.

Take dated photos of every room, the meters, and anything already worn or damaged on the day you move in, and do exactly the same on the day you move out. Get your landlord to acknowledge the move-in photos at the time, even just by message, so there's a shared record to point back to if a disagreement comes up later. This single habit resolves more deposit disputes than any clause in a contract.

If your deposit isn't returned

Start in writing: a message or email to the landlord asking for the deposit back, with your handover photos attached, resolves most cases without further steps. If that doesn't work, your options depend on your landlord's status:

• Landlord with 3+ units: file a complaint with the OCPB — by phone on hotline 1166, online at complaint.ocpb.go.th, or in person at any OCPB office. The service is free, and OCPB will typically acknowledge a complaint within about a week before attempting mediation.
• Private landlord (1–2 units): the OCPB route is not guaranteed to apply, since these landlords generally fall outside its consumer-protection notification. Your recourse is the civil court system instead.

For a straightforward dispute over an amount within reach of a deposit, Thailand's district-level Kwaeng Courts handle civil claims up to 300,000 THB under a simplified, faster procedure, according to the Court of Justice's own published threshold — a few commercial property sites quote a higher figure, but the official court threshold is the one to rely on. Above that amount, or for anything more complex, the case goes to the Provincial Court. Either way, it is worth a short consultation with a Thailand-qualified lawyer before filing, since procedural details vary and a lawyer can tell you quickly whether your case is straightforward or not.

Deposit checklist

• Ask your landlord upfront whether they rent out three or more units, or just this one
• Get the deposit amount, refund timeline and allowed deductions written into the contract
• Photograph every room, fixture and meter reading on move-in day, and get the landlord to acknowledge it
• Repeat the same photographed walkthrough on move-out day
• Ask for a written breakdown and evidence of cost for any deduction before accepting it
• If unresolved, go to OCPB (1166 or complaint.ocpb.go.th) first if your landlord qualifies as a business, otherwise consider the civil court route

For the practical side of finding a place before you get to any of this, see our guide on finding a long-term rental on Koh Samui, and our separate guide to spotting rental scams on Koh Samui if a deal looks too good to be true before you've even paid a deposit.

This article is general information, not legal advice — for a dispute specific to your lease, confirm the current rules with the OCPB hotline (1166) or a Thailand-qualified lawyer.

Frequently asked questions

How many months' deposit is normal for a rental on Koh Samui?

There's no official figure, but based on current listings and our local team's market contact, one to three months' rent is typical, usually alongside one month's rent paid in advance. It varies by property and landlord.

Is there a legal cap on the security deposit in Thailand?

Only for landlords who rent out three or more units as a business: since 4 September 2025, an OCPB rule caps deposit plus advance rent at three months' rent combined. Private landlords with one or two units are not subject to a legal cap — the contract decides.

How long does a landlord have to return my deposit?

For a landlord covered by the 2025 OCPB rule: immediately if there's no damage, within 7 days if an inspection is needed, and within 14 days for any remaining balance after deductions. For a private landlord with one or two units, there is no statutory deadline — check what your contract says.

Can my landlord deduct cleaning or air-conditioning servicing costs from my deposit?

Only if it's agreed in the contract or reflects damage or dirt beyond normal use — a routine end-of-tenancy clean or filter service is closer to normal wear and tear, which cannot be deducted under the 2025 rule for business landlords, and is worth disputing even with a private landlord.

What can I do if my landlord won't return my deposit?

Ask in writing first, with your handover photos. If that fails, and your landlord operates three or more rental units, file a free complaint with the OCPB (hotline 1166 or complaint.ocpb.go.th). Otherwise, a civil claim through the Kwaeng Court (for amounts up to 300,000 THB) or Provincial Court is the fallback route — a local lawyer can advise on your specific case.

Sources

Last checked: 19 September 2026. Facts were cross-checked against several sources; official ones take priority.

• Local knowledge of the properties-away team (2026-09-19)
• OCPB sample residential lease contract (PDF) (2026-06-08)
• OCPB WEB — สัญญาเช่าอาคาร เช่าอะพาร์ตเมนต์ ต้องจัดทำสัญญาเช่าอาคารตามแบบ (2026-07-20)
• Thailand Strengthens Controls on Residential Lease Contracts — Tilleke & Gibbins (2025-08-26)
• New rental contract control law in force: 3 units and up now covered (planliv.com) (2026-08-05)
• Thai Civil Procedure FAQ: Which court should the case be filed in? — Siam Legal (2026-09-19)
• How do I file a consumer complaint with OCPB? (2026-05-07)
• คำวินิจฉัยของประธานศาลอุทธรณ์ที่ 691/2568 (Court of Appeal President's ruling on business classification) (2026-02-16)
• Internal fact-check: 2026-09-19-mietratgeber-welle4.md, question 1 (security deposit) (2026-09-19)