The short answer
Many renters and buyers assume that once a Thai contract is signed, every clause in it binds them. Thai contract law does start from freedom of contract, but since the late 1990s a statute has let the courts step in where one side used its position to write the terms in its own favor. The clause is not struck out. It is enforced only to the extent that is fair. The table gives the position on each point, with the section it comes from.
| Question | Position in the Act | Basis |
|---|---|---|
| Which contracts are covered | A contract between a consumer and a business operator, any standard form contract, and a sale with a right of redemption | Section 4 |
| What makes a term unfair | It gives the operator, the party who set the form or the redemption buyer an advantage over the other side that is more than reasonable | Section 4 |
| What happens to an unfair term | It has effect only as far as is fair and reasonable in the circumstances | Section 4 |
| Unclear wording in a pre-printed form | Read in favor of the party who did not set the form | Section 4 |
| A deposit paid as earnest and then forfeited | The court may reduce a disproportionately high earnest to the actual damage | Section 7 |
| A clause excluding liability for defects in a consumer sale | Not allowed, unless the consumer already knew of the defect when contracting | Section 6 |
| A notice excluding liability for death or injury | Cannot be relied on where the harm was intentional or negligent | Section 8 |
| A clause saying the Act does not apply | Void | Section 11 |
| Who decides | A court, weighing the factors the Act lists | Sections 10 and 13 |
Section numbers refer to the Act on Unfair Contract Terms B.E. 2540 (1997), read in Thai in its Royal Gazette print on 14 November 2026. English wording on this page is our own rendering, not an official translation.
The Act is one of several layers that sit on top of a Thai lease or sale contract. Our guide to tenant rights in Thailand gives the wider picture for renters, and our guide to reading a Thai lease agreement walks through the clauses you are likely to meet.
Contracts the Act reaches
Section 4 opens three doors. A term can be tested under the Act if it sits in any one of these contracts.
- A contract between a consumer and a business operator. Both words are defined in section 3 and both definitions matter.
- A standard form contract. Section 3 defines it as a written contract whose essential terms were fixed in advance, in whatever form it is made, and which one of the parties uses in running its business. This door does not ask whether the other side is a consumer.
- A sale with a right of redemption. This is the arrangement, known in Thai as khai fak, in which an owner sells property and keeps a right to buy it back. The Act protects the seller against the buyer under that sale.
The definitions in section 3 decide who goes through the first door.
| Term | Definition in section 3 | In a rental or a purchase |
|---|---|---|
| Consumer | A person who contracts as buyer, lessee, hire-purchaser, borrower or insured, or under any other contract to obtain property, a service or another benefit for payment, where the contract is not made in order to trade in that property, service or benefit | A tenant renting a home to live in, or a buyer of a home, on the wording |
| Also a consumer | A person who contracts as guarantor of such a person and did not do so as a trade | A relative or friend who signs as guarantor for a tenant |
| Business operator | A person who contracts as seller, lessor, hire-purchase owner, lender or insurer, or under any other contract to provide property, a service or another benefit, where the contract is made in order to trade in it as that person's ordinary course of trade | A developer selling units, or a business that lets homes as its trade |
| Contract terms | Agreements and consent, and also announcements and notices made in order to exclude or limit liability | House rules, posted signs and disclaimers, as well as the lease itself |
The full Thai name of the second party is a business, trade or profession operator. This page shortens it to business operator.
The business operator definition turns on trading in the property or service as an ordinary course of trade. An apartment building run as a business fits those words easily. An individual who lets a single condo is harder to place, and the Act does not answer it. The standard form door has the same condition in another shape: the form must be one that a party uses in running its business. Treat the position of a one-unit owner as open, and do not assume the Act applies or does not apply until a lawyer has looked at the facts.
The definitions describe roles in a contract, not kinds of people. Nothing in the fifteen sections sets a condition of nationality or residence, so a foreign tenant or buyer is tested by the same words as anyone else. A lease guarantor is covered by name, which matters because guarantee wording is often the harshest part of a rental file. Our guide to guarantors and co-signers for Thai rentals explains what that role involves.
The test for an unfair term
The test in section 4 has two steps, and the Act keeps them apart.
- Does the term give one side an advantage? The third paragraph of section 4 says a term may be regarded as giving an advantage where its nature or effect is to make the other party perform, or carry a burden, beyond what a reasonable person could ordinarily expect. Nine examples follow.
- Is the advantage more than reasonable? Only an advantage that goes beyond what is reasonable makes the term unfair. The last paragraph of section 4 sends the court to the factors in section 10 to decide that.
A term that passes both steps is an unfair contract term. The consequence is written into the same sentence: it has effect only as far as is fair and reasonable in the circumstances of the case. The court does not rewrite the whole contract and it does not have to throw the clause away. It sets the point up to which the clause may still be used.
The second paragraph of section 4 adds a rule of interpretation. Where a standard form contract is open to doubt, it is read in the way that favors the party who did not set the form. A vague clause in a landlord's or developer's template is therefore read against the side that drafted it, before any question of fairness comes up.
The note of reasons printed at the end of the Act explains the thinking. Thai contract law rests on the freedom of the parties and the binding force of what they declare. The note says that parties with greater economic bargaining power had come to use that principle to take advantage of those with much less, and that the Act gives the courts guidelines for identifying unfair terms and the power to enforce them only as far as is fair and reasonable.
Nine examples written into the Act
The third paragraph of section 4 lists nine kinds of term. The list is introduced with the Thai word for “for example”, so it is not closed, and each item is something that may be regarded as giving an advantage. Being on the list does not make a clause unfair by itself. The court still asks whether the advantage is more than reasonable.
| No. | Kind of term in section 4 | Where a renter or buyer may meet it |
|---|---|---|
| 1 | Excludes or limits liability arising from a breach of contract | A clause saying the landlord or developer owes nothing if it fails to do what the contract requires |
| 2 | Makes a party liable, or carry a burden, beyond what the law prescribes | A clause loading one side with duties or costs that the law would not place on it |
| 3 | Ends the contract without reasonable cause, or lets one side terminate where the other has not breached a material term | A right to end the lease or cancel the sale at will |
| 4 | Lets one side not perform a term, or perform late, without reasonable cause | A handover or repair date the operator may push back as it pleases |
| 5 | Lets one side demand, or impose, a burden greater than the burden at the time of contracting | A right to raise charges or add obligations after signing |
| 6 | In a sale with a right of redemption, sets the redemption price above the sale price plus interest of more than fifteen percent a year | A buy-back price that hides a higher rate |
| 7 | In a hire-purchase contract, sets the price or the hirer's burden higher than is appropriate | Hire-purchase of a car or motorbike |
| 8 | In a credit card contract, makes the consumer pay interest, penalties, costs or other benefits higher than is appropriate on or in connection with default | Card default charges |
| 9 | Sets a method of compound interest that makes the consumer carry a burden higher than is appropriate | Interest charged on interest |
The middle column follows the Act. The right-hand column is our own illustration of where each kind of term can appear, not a ruling that any such clause is unfair.
Items 1 to 5 are general and can fit a lease, a reservation agreement or a sale and purchase agreement. Items 6 to 9 are tied to named kinds of contract. The fifteen percent figure in item 6 is the only number in the list.
Lease terms seen through the Act
The Act names the lessee as a consumer and the lessor as a possible business operator, so a home lease is squarely the kind of contract it was written for, provided one of the doors in section 4 is open. The clauses below are common in rental paperwork. For each one, the note shows which part of the Act a tenant would point to. None of this is a finding that the clause is unfair: that depends on the lease as a whole and on the factors in section 10.
- The landlord may end the lease at any time. Example 3: termination where the other side has not breached a material term. Our guide to eviction in Thailand sets out the lawful route for ending a tenancy.
- The landlord may change the rent or fees during the term. Example 5: a burden greater than the one at the time of contracting. Our guide to rent increases in Thailand covers what the lease rules say about it.
- The landlord is not responsible for any failure on its side. Example 1: excluding liability for a breach of contract.
- The tenant pays charges or penalties far above the loss caused. Example 2 may apply where the burden goes beyond what the law prescribes. Our guide to late rent fees in Thailand covers penalty clauses and the interest rules.
- The landlord may delay repairs or handover without reason. Example 4: late performance without reasonable cause.
- The tenant agrees that the Unfair Contract Terms Act does not apply. Void under section 11, whatever else the lease says.
Section 7 speaks of something given as earnest, the sum handed over when a contract is made. A rental security deposit is usually held to cover unpaid rent and damage. The Act does not say whether a security deposit counts as earnest, so this guide does not treat section 7 as a deposit rule for tenants. A clause letting a landlord keep the deposit can still be tested under section 4. Our guide to security deposits in Thailand and our guide to getting a rental deposit back cover the rules written for deposits.
The Act can also work for a landlord. A small owner who signs a management company's or an agency's pre-printed agreement is the party who did not set the form, and the standard form door in section 4 is not limited to consumers.
Earnest money and forfeiture on a purchase
Buyers in Thailand usually pay money at the start: a reservation fee, then a deposit on signing. Contracts commonly say that the seller keeps it if the buyer does not go through with the purchase. Section 7 is the part of the Act written for that moment.
It says that in a contract where something has been given as earnest, if the case is one where the earnest is to be forfeited and the earnest is disproportionately high, the court may reduce it so that only the amount of the actual damage is forfeited. Three points follow from the wording.
- It is not limited to consumers. The section speaks of any contract in which earnest was given. It does not use the words consumer, business operator or standard form.
- It is discretionary. The court may reduce the forfeiture. It is not required to, and nothing happens unless the matter comes before a court.
- The yardstick is actual damage. The section sets no percentage of the price above which an earnest is too high. The comparison is between the sum kept and the loss the seller really suffered.
For a buyer this changes the conversation with a seller who intends to keep a large payment after a sale falls through. The contract clause is the starting point, not the end, and the seller's real loss becomes relevant. It does not make a deposit refundable on request, and a buyer who walks away should expect to lose something.
The safest moment to deal with forfeiture is before paying. Our reservation agreement checklist lists what to settle in writing, and our guide to condo developer delays and refunds covers the buyer's position when it is the developer who fails to perform.
Defect waivers and liability notices
Sections 6, 8 and 9 deal with clauses and signs that try to remove liability in advance. They are stricter than the general test in section 4.
| Section | What it covers | Effect |
|---|---|---|
| 6 | A contract between a consumer and a business operator that is performed by handing over property, with a term excluding or limiting the operator's liability for defects or for a third party's better right to the property | The term is not allowed. If the consumer already knew of the defect or the cause when contracting, the term works only as far as is fair and reasonable |
| 8, first paragraph | A term, announcement or notice made in advance to exclude or limit liability, in tort or contract, for harm to life, body or health caused intentionally or negligently by the person giving it or by someone that person answers for | It cannot be relied on to exclude or limit liability |
| 8, second paragraph | Advance terms, announcements or notices excluding or limiting liability in other cases, where they are not void | They have effect only as far as is fair and reasonable |
| 9 | The injured person's agreement or consent to an act that the law expressly prohibits or that is contrary to public order or good morals | It cannot be relied on to exclude or limit liability in tort |
Section 8 does not use the word void for injury notices. It says the notice cannot be relied on, and this page keeps to that wording.
For a buyer, section 6 is the one to know. A developer or other seller in the trade that hands over a home to a consumer may not contract out of responsibility for defects, or for a third party turning up with a better right to the property. An “as is” clause only has room to work where the buyer already knew of the specific defect at the time of the contract, and even then only to a fair extent. Section 6 is written for consumer contracts, so a sale between two private individuals is not within its words. Our guide to condo handover and defect inspection and our house defect warranty checklist cover finding and recording defects.
For a resident, section 8 reaches the notices seen around buildings: by a pool, in a gym, in a car park, in house rules. The definition of contract terms in section 3 includes announcements and notices made to exclude or limit liability, so a sign counts. A notice cannot remove liability for an injury caused by negligence. A notice about loss of or damage to belongings falls in the second paragraph and is tested for fairness. Our guide to condo common area rules covers how those spaces are run.
Factors a court weighs
Section 10 tells the court to consider all the circumstances in deciding how far a term can be enforced and still be fair and reasonable. It then lists four groups of factors.
- The parties as they really are. Good faith, bargaining power, economic standing, knowledge and understanding, experience, expectations, how the parties dealt with each other before, the other choices open to them, and everything each side stood to gain or lose.
- The ordinary practice for that kind of contract.
- The time and place at which the contract was made or is to be performed.
- The much heavier burden carried by one party when compared with the other.
The first group explains why the same clause can fare differently in two cases. A tenant handed a Thai-language template on the day of moving in, with no chance to change a word, stands differently from a company that negotiated a lease through lawyers over several weeks. Language is not named in the list, but knowledge and understanding are, and so are the alternatives the party had.
Two procedural sections support the court. Section 13 lets it call a qualified person or expert to give an opinion, at a party's request or on its own initiative, and section 14 deals with that person's fees. Section 5 applies the same fair-and-reasonable approach to clauses that restrict a person's right to work or do business, such as a non-compete clause, and has the court look at the area and period of the restriction and the person's ability to earn a living in another way.
The Act beside the standard lease contract rules
The Unfair Contract Terms Act is not the only control on what a Thai lease may say. Residential leasing is also a contract-controlled business under the Consumer Protection Act. The two work in different ways.
| Point | Unfair Contract Terms Act B.E. 2540 | Contract-controlled business rules |
|---|---|---|
| Where it comes from | An Act, with the Minister of Justice in charge under section 15 | A notification of the Contract Committee, administered by the Office of the Consumer Protection Board |
| How it works | A general test applied after the event to whatever the contract says | Rules set in advance on what the contract must and must not contain |
| Who applies it | A court, in a case between the parties | The Office of the Consumer Protection Board, which inspects operators |
| Read for this guide | All fifteen sections | Two news items from the Office; the notification itself is covered in our other guides |
The Office of the Consumer Protection Board published a news item on 8 June 2026 under a heading that says building and apartment leases must be made on the standard contract form. It names the Contract Committee notification making residential building leasing a contract-controlled business B.E. 2568, dated 30 May 2025, and links a sample short-term residential lease. An earlier item of 30 January 2026 reports that officers inspected residential leasing businesses in Udon Thani from 27 to 29 January 2026 under that notification.
Those rules are specific where the Act is general. Our guides to rent increases, eviction and late rent fees set out which landlords the notification covers and the clauses it bars, and our guide to consumer complaints in Thailand explains how to bring a complaint to the Office.
Nothing read for this guide states how the two instruments interact. On their own terms they are separate: one gives the Office rules to enforce against operators, and the other gives a court a test to apply to any covered contract. A tenant whose landlord is outside the notification, or whose problem is a clause the notification does not mention, may still have an argument under the Act.
Using the Act before you sign and after a dispute starts
The Act names no complaints office and sets no fine. It speaks to the court. That shapes how a tenant or buyer can use it in practice.
- Negotiate first. The Act is a fallback. A clause you had struck out before signing never needs a judge. Ask for one-sided termination, variation and forfeiture clauses to be removed or made mutual.
- Keep a record of how the contract was made. Section 10 looks at bargaining power, understanding and alternatives. Save the messages that show whether changes were refused, how long you had to read the document and whether an English version was offered.
- Do not rely on a clause that excludes the Act. It is void under section 11, so signing it gives nothing away.
- Raise the Act in writing when a dispute starts. A short letter naming the clause, the example in section 4 it resembles and the outcome you propose often moves a negotiation, because the other side knows a court could cut the clause back.
- Know where the claim would be heard. Our guide to small claims court in Thailand explains the courts and the consumer case procedure a tenant or buyer would use.
- Take advice before withholding money. Until a court has ruled, the clause is still in the contract. Stopping rent or installments on the strength of your own view of fairness can put you in breach. Our guide to hiring a lawyer in Thailand covers finding one.
Section 12 says the Act does not apply to a juristic act or contract made before the day it came into force. The Act was given on 14 November 1997 and section 2 brought it into force 180 days after its publication in the Royal Gazette. Any lease or sale signed in recent years is well after that point.
The Act was read in its Royal Gazette print of 1997. A consolidated text was not found, so this guide did not check whether any section has been amended since. No court decision was read, so the page says what the Act provides and not how judges have applied it to a particular lease or sale. Two questions are left open because the text does not answer them: whether an owner who lets one home is a business operator, and whether a rental security deposit is earnest under section 7. The examples of lease and sale clauses are our own illustrations.
Buyers paying in stages for a home that is not yet built face the largest sums and the longest contracts. Our guide to buying off-plan property in Thailand and our guide to the buying process cover the rest of that journey.
Frequently asked questions
Only in part. Section 4 of the Unfair Contract Terms Act B.E. 2540 says a term that gives a business operator, or the party who wrote a standard form contract, an unreasonable advantage is an unfair term and has effect only as far as is fair and reasonable in the circumstances. A court decides how far that is. The term is cut down, not automatically erased.
Not as a rule. The Act's main remedy is that the clause is enforced only to a fair and reasonable extent. Two things go further. A clause saying the Act does not apply is void under section 11, and an advance notice excluding liability for death or injury caused on purpose or by negligence cannot be relied on at all under section 8.
Signing does not switch the Act off. It applies to terms the parties agreed, and section 11 voids any clause that tries to exclude it. What signing can affect is the result: section 10 has the court weigh knowledge and understanding, bargaining power, other choices open to you and the usual practice for that kind of contract.
The definition in section 3 names a lessee, along with a buyer, a hire-purchaser, a borrower and an insured person, as long as the contract is not made in order to trade in the thing obtained. A person who guarantees such a consumer, and does not do so as a trade, is covered too.
The text does not settle it. The consumer route in section 4 needs a business operator, defined as someone who contracts as lessor or seller in order to trade as that person's ordinary course of trade. A standard form contract is covered separately, but only where a party uses the form in running its business. Whether a one-unit owner fits either description is for a court.
Not always. Under section 7, where something was given as earnest and it falls to be forfeited, the court may reduce an earnest that is disproportionately high so that only the amount of the actual damage is kept. The power is discretionary, so the buyer has to ask a court to use it.
Not against a consumer. Section 6 says a contract between a consumer and a business operator that is performed by handing over property may not exclude or limit the operator's liability for defects or for a third party's better right, unless the consumer already knew of the problem when the contract was made. Even then the clause works only as far as is fair.
Section 8 says a term, announcement or notice made in advance to exclude or limit liability for harm to life, body or health cannot be relied on where the harm was caused on purpose or by the negligence of the person who gave the notice, or of someone that person answers for. Notices about other loss are enforceable only as far as is fair and reasonable.
A court, in a case between the parties. The Act names no complaints office and sets no fine. Section 10 lists what the court weighs and section 13 lets it call an expert. The Minister of Justice is in charge of the Act under section 15.
The definitions of consumer and business operator in section 3 describe roles in a contract, such as buyer, lessee, seller and lessor. Nothing in the fifteen sections read for this guide sets a nationality or residence condition.
No. Section 12 says the Act does not apply to a juristic act or contract made before the day it came into force. The Act was given on 14 November 1997 and section 2 brought it into force 180 days after publication in the Royal Gazette.
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General information only, not legal advice. The sections of the Act on Unfair Contract Terms B.E. 2540 are from its Royal Gazette print, read in Thai on 14 November 2026; the English wording is our own rendering and later amendments, if any, were not checked. No court decision was read. The statements about the residential leasing notification are from two news items of the Office of the Consumer Protection Board. The examples of lease and sale clauses are illustrations, not findings that any clause is unfair. Take advice from a Thai lawyer on your own contract before acting.
Sources
- Act on Unfair Contract Terms B.E. 2540 (Thai, Royal Gazette print, 5 pages), given 14 November 1997: s.2 in force 180 days after publication, s.3 definitions of contract terms, consumer, business operator and standard form contract, s.4 the test and nine example terms, s.5 restraints on occupation, s.6 defect waivers in consumer contracts, s.7 reduction of a forfeited earnest, s.8 and s.9 liability notices and consent, s.10 factors for the court, s.11 a term excluding the Act is void, s.12 earlier contracts, ss.13-15 experts and the Minister of Justice, and the note of reasons; original print, later amendments not checked ↗Royal Thai Government Gazette, Secretariat of the Cabinet · Accessed 14 November 2026
- OCPB news item of 8 June 2026: building and apartment leases must be made on the standard contract form; names the Contract Committee notification on residential building leasing as a contract-controlled business B.E. 2568 (dated 30 May 2025) and links a sample short-term residential lease ↗Office of the Consumer Protection Board, Kingdom of Thailand · Accessed 14 November 2026
- OCPB news item of 30 January 2026 (Thai): officers inspected residential building leasing businesses in Udon Thani on 27 to 29 January 2026 under the Contract Committee notification B.E. 2568 and the Consumer Protection Act B.E. 2522 ↗Office of the Consumer Protection Board, Kingdom of Thailand · Accessed 14 November 2026
Official primary sources are listed above with the date we last checked them. Thai rules, fees, thresholds and procedures change and can be applied differently by individual offices and embassies — confirm the current requirement with the responsible authority before relying on it. General information only, not legal, tax or medical advice. BAANLYY never takes paid placement in editorial content.