Thailand Patent Guide 2026: Invention Patents, Petty Patents and Designs for US and Foreign Companies, PCT Entry, Fast-Track Options and the Draft Patent Act
Po-Chang Yu (Raymond Yu) Chief Lawyer / Founder and CEO of Louis Group 
Key takeaways
- Thailand's Patent Act gives three kinds of protection: invention patents (20 years), petty patents (6 years, extendable twice by 2 years, with no substantive examination before registration) and design patents (10 years).
- A US applicant has two routes in: the PCT, with national-phase entry in Thailand 30 months from the priority date, or a direct filing under the Paris Convention within 12 months of the first filing (6 months for designs). Either way the application has to be in Thai.
- The US one-year grace period does not travel. Thailand's grace period is narrow, so a paper, a trade-show demo or a product launch before the first filing can cost you the Thai patent even where it costs nothing in the United States.
- A standard invention patent takes roughly 4 to 6 years, and longer in chemistry and pharmaceuticals. There is no patent prosecution highway between Thailand and the USPTO; Thailand's only PPH partner is Japan.
- Computer programs as such, business methods and methods of medical treatment are not patentable. There is no patent term extension, and USTR's 2026 Special 301 Report again notes the lack of effective protection for pharmaceutical test data.
- An invention made by an employee in the course of employment belongs to the employer, but the employee keeps a right to remuneration that cannot be excluded by contract.
- A draft of a new Patent Act went to public consultation in December 2024 and had not been enacted as of November 2026. It would raise official fees sharply, shorten the time to request examination and extend the design term to 15 years.
Twenty years ago I was not yet a lawyer. I was a patent engineer. After graduate school in engineering and a period in defence research, I joined a patent firm in Taipei, where my job was to turn clients' inventions into patent specifications and file them in the United States, Japan, Europe, China and Southeast Asia. I watched portfolios grow from nothing to several hundred patents, one country decision at a time.
I later trained as a lawyer, and the practice widened from patents to corporate law and cross-border investment, and then to offices in Thailand and Vietnam. One lesson from the first career has stayed with me: the patent usually leaves home before the factory does.
Thailand has changed in those twenty years. It is no longer only a place where foreign companies manufacture; it is one of ASEAN's largest markets for vehicles, electronics and processed food. The question clients ask has changed with it, from "should we file in Thailand at all?" to "what will the new Patent Act cost us, and should we file before it arrives?" This guide sets out the Thai patent system as a US or other foreign company meets it. It reflects Thai law and the practice of the Department of Intellectual Property (DIP) as of November 2026.
1. Three kinds of protection: invention patents, petty patents and designs
| Item | Invention patent | Petty patent | Design patent |
|---|---|---|---|
| What it protects | A technical invention, product or process | The same, at a lower level of inventiveness | The shape, pattern or colour of a product |
| Requirements | Novelty, inventive step, industrial applicability | Novelty and industrial applicability; no inventive step required | Novelty and industrial applicability |
| Examination | Formality check, publication, then substantive examination on the applicant's request | Registered and published after a formality check; no substantive examination | Formality check, publication, substantive examination |
| Term | 20 years from filing | 6 years from filing, extendable twice by 2 years each, 10 years in total | 10 years from filing |
| Typical time to grant | 4 to 6 years; 1 to 2 years on a fast-track route | 1 to 2 years | 2 to 3 years |
| Current official fees | THB 500 to file, THB 250 to request examination, THB 500 on grant; annuities from the fifth year | THB 250 to file, THB 500 on registration | THB 250 to file |
| Best suited to | Core technology, chemical formulations, processes | Mechanical improvements, moulds, jigs, packaging structures | Product appearance |
1.1 The petty patent: the right US companies most often overlook
The United States has no utility model, so US companies tend not to think about one. Thailand's petty patent protects an invention that is new and industrially applicable without asking for an inventive step, and it is registered after a formality check alone. For process improvements, tooling and packaging developed at a Thai plant it is the cheapest and fastest protection available, and the certificate can be in hand in a year or so.
Two points need watching.
- The term has to be extended. The initial term is 6 years. It can be extended twice, by 2 years each time, and a missed extension ends the right.
- Have it examined before you enforce it. Because a petty patent is registered unexamined, an interested party can ask the DIP to examine it after publication. In practice an owner who plans to send a warning letter or sue should first make sure the right will survive examination, or the defendant will use the request to stall.
1.2 Designs: novelty is absolute
A Thai design must not have been disclosed anywhere before the Thai filing date. A design shown at an exhibition in Las Vegas or listed on an online store before filing is no longer new. File the design first and launch second.
The draft Patent Act would extend the design term to 15 years, recognise partial designs and prepare for accession to the Hague Agreement on the international registration of designs. The Thai parliament approved accession in 2022, and the United States has been urging Thailand to finish the job. For the brand side of the same product, see Trademark Registration in Thailand 2026 for US and Foreign Brands: Fast Track 4 Month Plus+, Madrid vs Direct Filing, and the First-to-File Rule .
2. Getting into Thailand: the PCT, the Paris Convention and the Thai text
Thailand is a member of both the Paris Convention and the Patent Cooperation Treaty, which it joined in 2009. A US applicant can use either.
| Route | Deadline | What is needed in Thailand | When it fits |
|---|---|---|---|
| PCT national phase | 30 months from the priority date | Entry through a Thai agent; the title, claims and abstract in Thai at entry | Inventions going to many countries, where the extra 18 months to decide is worth having |
| Paris Convention direct filing | 12 months from the first filing for inventions and petty patents; 6 months for designs | A Thai application claiming priority, with a certified copy of the priority document | Two or three target countries, or a case that needs to start moving in Thailand early |
| Direct filing without priority | Before any public disclosure | A Thai application | Inventions made in Thailand and first filed there |
2.1 Everything is examined in Thai
The specification, claims and abstract are filed and examined in Thai. For a PCT application the title, claims and abstract must be in Thai when the national phase is entered. Practice on filing the rest of the translation later has varied, so the safe plan is to have the complete Thai text ready by the 30-month date.
The quality of the translation decides the scope of the claims. The usual mistake is a literal translation by a general translation agency, in which the technical terms do not match the terms Thai examiners use, and the result is round after round of office actions. Have the Thai text reviewed by a Thai patent agent with an engineering background.
2.2 The US grace period does not travel
Under US law an inventor's own disclosure in the year before filing does not count against the application. US companies and universities plan around that rule: publish, present, then file.
Thailand's exception is much narrower. Broadly, it covers a disclosure that results from an unlawful act and the inventor's own display at an international or officially recognised exhibition, in the 12 months before filing. A journal article, a conference talk, a pitch deck sent without a confidentiality agreement or a product page is not something to rely on. If Thailand, or most other countries outside the United States, is on the filing list, file before you disclose.
2.3 Check the US side before filing abroad
For an invention made in the United States, US law requires a foreign filing licence before a patent application is filed in another country, or a wait of six months after the US filing. The licence normally arrives with the US filing receipt, so a company that files first in the United States and then enters Thailand through the PCT or the Paris Convention rarely has a problem. The point to watch is the reverse case: a team working partly in the United States and partly in Thailand that wants to file first in Thailand. Decide where the invention was made before choosing the office of first filing.
3. Procedure and timing for an invention patent
| Stage | What happens | Timing |
|---|---|---|
| 1. Filing | Thai application filed with the DIP through its e-filing system | Filing date |
| 2. Formality examination | Completeness of documents, unity of invention | About 6 to 12 months |
| 3. Publication | Published once the formality examination is passed; 90 days for opposition | Publication date |
| 4. Request for substantive examination | Must be filed within 5 years of publication under the current Act, or the application is deemed abandoned | Best filed immediately after publication |
| 5. Substantive examination | Office actions and responses | 2 to 4 years, depending on the technical field |
| 6. Grant | Fees paid within the period stated in the notice | As notified |
| 7. Annuities | Due from the fifth year; can be paid in a lump sum | Yearly |
A US applicant is used to examination starting by itself. In Thailand nothing happens after publication unless the applicant asks for examination, and the five-year window is long enough to forget.
3.1 Ways to speed things up
| Route | Condition | Effect |
|---|---|---|
| PPH with Japan | The same invention has been allowed by the Japan Patent Office and the Thai claims correspond to the allowed Japanese claims. The JPO and the DIP extended the programme for a further two years from 1 January 2026 | The DIP works from the Japanese result |
| ASPEC | The same invention has a search and examination result from another participating ASEAN office, such as Singapore, Malaysia or Vietnam | Examination is accelerated on the basis of that result, which the Thai examiner treats as a reference and not as binding |
| Target Patent Fast Track | The invention falls in a field designated by the DIP: medical and public health (from 2022), future food (from 2023), green technology (from 15 December 2024). No more than 10 claims; the DIP selects a limited number of applications each month | A first office action within about 12 months of publication for inventions, with no additional official fee |
There is no PPH between Thailand and the USPTO. A US company that also holds a Japanese patent for the same invention can use the Japan route, and one that has a Singapore result can use ASPEC. For everyone else, the practical step is to keep the Thai claims aligned with the claims granted in the United States or Europe and to give the Thai examiner the foreign search and examination results as soon as they exist.
4. What cannot be patented, and what US pharmaceutical companies should know
Section 9 of the Patent Act excludes:
- naturally occurring microorganisms and their components, animals, plants and extracts from them;
- scientific and mathematical rules and theories;
- computer programs;
- methods of diagnosing, treating or curing human or animal diseases;
- inventions contrary to public order, morality, health or welfare.
In practice:
- Software. A program as such is excluded. An invention that uses a program as part of a technical system or process can qualify if it meets the ordinary requirements, but examination is strict.
- Business methods. These are refused, usually as programs or as abstract rules.
- Second medical use. Claim format matters. Some formats accepted elsewhere are not accepted in Thailand, and the claims usually need reworking by the Thai agent.
For pharmaceuticals, three further points shape the commercial life of a patent.
- No term extension. Thailand has no patent term adjustment or extension to compensate for examination or regulatory delay. With examination in the pharmaceutical field taking as long as it does, the effective term can be short. USTR's 2026 Special 301 Report records that the backlog remains high in the pharmaceutical sector.
- No effective data exclusivity. The same report states that Thailand does not provide an effective system for protecting undisclosed test data submitted for marketing approval of pharmaceutical and agricultural chemical products.
- Compulsory licences. The Act allows government use, and a compulsory licence where a patent has not been worked within three years of grant or four years of filing. Between late 2006 and early 2008 the Thai government issued government-use licences over several patented medicines for HIV, heart disease and cancer, some of them owned by US companies. A patent that will not be worked in Thailand for years carries that risk.
The differences a US applicant most needs to keep in mind:
| Point | United States | Thailand |
|---|---|---|
| Grace period for the inventor's own disclosure | 12 months | Narrow: unlawful disclosure, or display at an international or official exhibition, within 12 months before filing |
| Second-tier patent | None | Petty patent, registered without substantive examination |
| Software and business methods | Patentable in principle, subject to the case law on abstract ideas | Programs as such excluded; business methods refused in practice |
| Methods of treatment | Patentable | Excluded |
| Term adjustment or extension | Available | None |
| Request for examination | Not needed | Required within 5 years of publication |
| Employee inventions | Mainly a matter of contract | Employer owns by statute; the employee's right to remuneration cannot be waived |
| Language | English | Thai |
| Criminal liability for infringement | None | Yes |
5. Employee inventions: who owns what your Thai engineers invent
Sections 11 and 12 of the Patent Act provide the following.
- An invention made in the performance of an employment contract or a contract to do work belongs to the employer, unless the contract says otherwise.
- The employee nevertheless has a right to remuneration where the employer benefits from the invention. The parties cannot agree that right away. The employee applies to the Director-General of the DIP, who fixes the amount.
- The same applies where the invention was not part of the employee's duties but was made using the employer's means, data or reports.
A US employer is used to an invention assignment clause settling the matter. In Thailand the clause settles ownership, but it does not remove the right to remuneration, and a provision that says it does will not be enforced.
The more common problem is the chain of title. An engineer at the Thai subsidiary improves a process, and the application is filed in the name of the US parent. Under Thai law the invention belongs first to the Thai subsidiary as employer, so the parent needs a written assignment from the subsidiary. Without it, an infringer can later argue that the applicant was never entitled to apply, which is a ground for invalidating the patent under section 54. The same chain is a standard item in intellectual property due diligence when a Thai company is bought; see Buying a Company in Thailand 2026: Share Deal vs Asset Deal, the 49% Rule, Licence Succession, Merger Control and a 12-Point Due Diligence Checklist for Foreign Buyers .
Licensing into Thailand
A patent licence must be in writing and registered with the DIP. Terms that unfairly restrict competition are void, and that includes tying arrangements and an obligation to keep paying royalties after the patent has expired. A US licence template usually needs adjusting before it is registered. Where the technology is going into a Thai joint venture, decide in the shareholders' agreement who owns improvements and what happens to the licence if the venture ends; see Joint Ventures and Shareholders' Agreements in Thailand 2026: Where Lawful Protection Ends and a Nominee Structure Begins under the New DBD Checks .
6. Enforcement: what patent litigation looks like in Thailand
6.1 Court and procedure
Patent cases are heard at first instance by the Central Intellectual Property and International Trade Court (IP&IT Court), which has exclusive jurisdiction, with appeal to the Court of Appeal for Specialized Cases.
- The court can appoint technical experts to assist it.
- Preliminary injunctions and orders to preserve evidence are available, but the court is cautious about granting an injunction in a patent case and expects clear infringement and harm that damages cannot repair.
- For a process patent, the burden of proof can shift to the defendant once the patentee shows that the defendant's product is identical or similar to the product of the patented process.
- First instance usually takes about 12 to 24 months.
6.2 Civil and criminal remedies
| Remedy | Content |
|---|---|
| Civil | Injunction, damages for actual loss, lost profit and enforcement expenses, and destruction of infringing goods |
| Criminal | Infringing an invention patent or a design patent: up to 2 years' imprisonment, a fine of up to THB 400,000, or both. Infringing a petty patent: up to 1 year, a fine of up to THB 200,000, or both |
| Border measures | Customs detention is used mainly in trademark and copyright cases; a patent case needs a detailed technical comparison |
Criminal liability for patent infringement surprises US companies, since US law has none. In Thailand it changes the tactics. Rights holders often combine a warning letter with a criminal complaint: the police can search and seize, and the civil claim or a settlement follows from a stronger position and faster than a purely civil action.
Check validity before sending the warning letter. Thai law allows the recipient to sue for a declaration of non-infringement and to seek invalidation.
6.3 Invalidation
An interested person can ask the IP&IT Court to invalidate a patent under section 54. The grounds include lack of novelty or inventive step, an applicant who was not entitled to apply, and insufficient disclosure. The current Act has no administrative invalidation procedure before the DIP; the draft Act would add one.
7. The draft Patent Act: should you file before it takes effect?
The DIP put a draft of an entirely new Patent Act to public consultation from 16 December 2024 to 31 January 2025. The draft expands the Act from 88 sections to 171. It had not been enacted as of November 2026, and USTR's 2026 report describes Thailand as continuing to make progress on it. The direction is clear, and the figures below are those of the public-consultation version.
| Item | Current Act | Draft |
|---|---|---|
| Filing fee for an invention | THB 500 | THB 3,500 for the first 30 pages, plus THB 40 per additional page; reductions may be set later by ministerial regulation |
| Substantive examination fee | THB 250 | Much higher: THB 10,000 in the consultation draft, plus THB 2,000 for each claim over 10 |
| Time to request examination | 5 years from publication | 3 years from filing |
| Publication | Once, after the formality examination | A first publication 18 months from filing and a second before grant |
| Opposition | 90 days from publication | 90 days from the pre-grant publication |
| Third-party observations | No express provision | At any time before grant |
| Request to examine a petty patent | By an interested person within 1 year of publication | By anyone at any time; an invention application and a petty patent application can be converted into each other within 3 years of filing |
| Design term | 10 years | 15 years, as 5 years plus two renewals of 5 years |
| Design novelty | Absolute | Absolute, with a grace period |
| Partial designs | Not recognised | Recognised |
| Hague Agreement | Not yet a member | A dedicated chapter to support accession |
| Deferred publication of designs | Not available | Available on request |
What this means for filing decisions
- Fees. The official fees would rise several times over, but they would still be small next to translation and agent costs. There is no need to rush a filing to save fees. An invention that is ready anyway will save the difference in examination fees if it is filed before the new Act takes effect.
- Three years to request examination. The current five-year window from publication is often used to wait and see how the market develops. Under the draft the decision to pay for examination would have to be made within three years of filing, so portfolio decisions come earlier.
- Designs. For appearance-led products there is an argument for waiting to file designs under the new Act and its 15-year term, but only if the design stays undisclosed until then. If it has already been shown, the current Act is the only route.
8. Cost estimates under the current Act
| Item | Official fee (THB) | Agent fee, for budgeting (THB) |
|---|---|---|
| Invention application, including a 20-page Thai translation | 500 | 40,000 to 80,000, most of it translation |
| Request for substantive examination | 250 | 10,000 to 20,000 |
| Response to an office action, each | None | 15,000 to 30,000 |
| Grant | 500 | 5,000 to 10,000 |
| Annuities, years 5 to 20 in total | About 150,000 | None |
| Petty patent, filing to registration | 250 plus 500 | 25,000 to 45,000 |
| Design patent, filing to grant | 250 plus 500 | 20,000 to 35,000 |
Agent fees vary widely with the firm and the complexity of the technology. The table is a budgeting aid, not a quotation.
Frequently asked questions (FAQ)
Can a US company use the PCT to get a patent in Thailand?
Yes. Thailand has been a PCT member since 2009. The application must enter the Thai national phase within 30 months of the priority date, through a Thai agent, with the title, claims and abstract in Thai at entry. Have the full Thai translation ready by the same date. The alternative is a direct filing under the Paris Convention within 12 months of the first filing.
How long does an invention patent take in Thailand?
Usually 4 to 6 years, and longer in chemistry and pharmaceuticals. Substantive examination starts only when the applicant requests it, which must be done within five years of publication. The PPH with Japan, ASPEC and the DIP's Target Patent Fast Track can bring the time down to roughly one to two years where the conditions are met.
Is there a patent prosecution highway between the USPTO and Thailand?
No. Thailand's only PPH partner is the Japan Patent Office, and that programme was extended for two years from 1 January 2026. A US company with a Japanese patent for the same invention can use it. Otherwise, keep the Thai claims aligned with the claims granted in the United States or Europe and give the examiner the foreign results.
We presented the invention at a conference before filing. Can we still patent it in Thailand?
Probably not. The US one-year grace period for the inventor's own disclosures has no real equivalent in Thailand, where the exception is limited broadly to unlawful disclosures and to the inventor's display at an international or officially recognised exhibition within 12 months before filing. Have a Thai agent check the facts before giving up, and file before disclosing next time.
What is a petty patent, and should a US company bother with one?
It is a second-tier patent for inventions that are new and industrially applicable but need not show an inventive step. It is registered without substantive examination, usually within one to two years, and lasts 6 years with two extensions of 2 years. It suits tooling, mechanical improvements and packaging developed at a Thai plant. Have it examined before you enforce it.
Can software be patented in Thailand?
A computer program as such cannot, and business methods are refused in practice. An invention in which a program forms part of a technical system or process can qualify if it is new, inventive and industrially applicable, but examiners are strict. The code itself is protected by copyright.
Our Thai subsidiary's engineer made the invention. Can the US parent file in its own name?
Only with a written assignment. Under section 11 of the Patent Act the invention belongs to the employer, which is the Thai subsidiary. Without an assignment from the subsidiary to the parent, the patent can later be attacked on the ground that the applicant was not entitled to apply. The engineer also keeps a right to remuneration that cannot be waived by contract.
When will the new Patent Act take effect, and how much will fees rise?
No date has been set. The draft finished public consultation on 31 January 2025 and had not been enacted as of November 2026. In the consultation version the filing fee for an invention rises from THB 500 to THB 3,500 and the examination fee from THB 250 to THB 10,000, the time to request examination becomes three years from filing, and the design term becomes 15 years.
How Louis Group can help
Twenty years ago I filed clients' patents in the United States, Japan and Europe, and nobody asked about Thailand. Today Thailand is a major production base and market in ASEAN, and its patent system is about to go through its largest reform in thirty years: higher fees, earlier deadlines, a longer design term and Hague membership. For a foreign company the question is rarely whether to file. It is whether to file now under the current Act or later under the new one, and whether the chain of title between the parent, the Thai subsidiary and the engineers who made the invention has been put in writing.
Louis Patent Office in Taipei works with Louis Group's Bangkok office on patentability assessments, review of Thai translations, PCT and Paris Convention filing strategy, PPH and ASPEC requests, employee invention assignments and remuneration, licence registration, and infringement warnings and litigation in Thailand.
Author: Po-Chang Yu (Raymond Yu) , Chief Lawyer, Founder and CEO of Louis Group, and Chief Technical Adviser to Louis Patent Office. A patent engineer before he became a lawyer, he has spent twenty years building international patent portfolios for manufacturing clients and leads Louis Group's cross-border practice in Thailand and Vietnam.
This article is based on the Thai Patent Act and DIP practice as of November 2026. The draft Patent Act is described as it stood in the public-consultation version and may change before enactment. Timelines and agent fees are estimates. This article is general information and is not legal advice on any particular case; consult a qualified lawyer or Thai patent agent before filing.
Related reading
- Trademark Registration in Thailand 2026 for US and Foreign Brands: Fast Track 4 Month Plus+, Madrid vs Direct Filing, and the First-to-File Rule
- Buying a Company in Thailand 2026: Share Deal vs Asset Deal, the 49% Rule, Licence Succession, Merger Control and a 12-Point Due Diligence Checklist for Foreign Buyers
- Joint Ventures and Shareholders' Agreements in Thailand 2026: Where Lawful Protection Ends and a Nominee Structure Begins under the New DBD Checks