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File a Thai Patent as a Foreign Inventor: The Guide
Foreign inventors file Thai patents via a Thai-resident agent under the Patent Act B.E. 2522 (1979). Thailand grants invention patents (20 years), petty patents (10 years total), and design patents (10 years). This guide explains each path.
TL;DR
Thailand grants invention patents (20 years), petty patents (sometimes called utility models, 6-year initial + extensions to 10 years), and design patents (10 years) under the Patent Act B.E. 2522 (1979), as amended. Foreign applicants file via a Thai-resident agent with the Department of Intellectual Property (DIP, Ministry of Commerce). Thailand is a PCT contracting state; PCT-national-phase entry is the most common path for foreign inventors.
The Three Patent Types
| Type | Threshold | Term | Use case |
|---|---|---|---|
| Invention patent | Novelty + inventive step + industrial applicability | 20 years from filing | Most inventions |
| Petty patent | Novelty + industrial applicability (no inventive-step test) | 6 years + two 2-year renewals (10 total) | Incremental innovations |
| Design patent | Novelty in shape / appearance | 10 years from filing | Industrial design |
Filing Routes
- Direct national filing — file Thai patent application with DIP. Translation into Thai required.
- PCT national-phase entry — within 30 months of the PCT priority date, file the Thai national-phase request with translation and the prescribed forms.
- Paris Convention priority — file within 12 months of a foreign first-filing claiming priority.
Examination Process
- Formality check (1-3 months).
- Publication after 18 months from priority.
- Substantive examination on request (within 5 years for invention patents).
- Acceptance or refusal; office actions; opposition window 90 days post-publication for invention patents.
- Grant + 5-yearly annuity payments.
Costs (Indicative)
- Government filing fee: THB 500-1,000 depending on type.
- Translation: THB 10,000-30,000 depending on length.
- Agent fees: THB 30,000-80,000 for full prosecution.
- Annuities: escalating from THB 1,000 to THB 60,000 over the term.
Common Mistakes
- Missing the 30-month PCT national-phase deadline.
- Inadequate Thai translation of claims — affects scope.
- Selecting petty patent when an invention patent would be available — petty patents are not assertable against later inventive-step prior art.
- Forgetting annuity payments — patent lapses.
FAQs
1. Can I file in English first?
The application must be in Thai. Translation can follow the filing as a formality, but the official-language version controls.
2. Is software patentable?
Pure software is excluded under §9; software-implemented inventions with technical effect can be examined as inventions.
3. Petty vs invention — which to choose?
Petty for short-life incremental innovations with strong novelty but weak inventive-step; invention for breakthrough technology.
Related Reading
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