An invention patent is protected for 20 years from the filing date and cannot be renewed the way a trademark can - but keeping that protection alive for the full 20 years requires paying annual fees on schedule. Miss them, and the patent can be revoked before its term ends.
What Annual Fees Are, and How They Differ from Filing Fees
The application fee, examination fee, and announcement fee are one-time costs during the application process. Annual (maintenance) fees are a recurring cost you pay every year after the patent is granted, to keep it in force for the rest of its 20-year term. This is not a renewal fee - an invention patent has no renewal system the way a trademark does.
Fee Schedule, Years 5-20
Verified live against the Department of Intellectual Property's fee schedule (ipthailand.go.th/th/patent-006.html) on 2026-07-31:
| Year | Fee (THB) | Year | Fee (THB) |
|---|---|---|---|
| 5 | 1,000 | 13 | 8,200 |
| 6 | 1,200 | 14 | 10,000 |
| 7 | 1,600 | 15 | 12,000 |
| 8 | 2,200 | 16 | 14,200 |
| 9 | 3,000 | 17 | 16,600 |
| 10 | 4,000 | 18 | 19,200 |
| 11 | 5,200 | 19 | 22,000 |
| 12 | 6,600 | 20 | 25,000 |
The fee increases as the patent ages (the longer you keep it, the more you pay per year), or you can pay a single lump sum of THB 140,000 instead of paying year by year (see the conditions in the next section).
The figures above are government fees, confirmed against the Department of Intellectual Property - clearly separate from Patent To You's professional service fees.
When Payment Starts and the Deadline
Annual fees start from year 5 of the patent's term. Payment is due within 60 days of the start of that year 5 period, and every year after (Patent Act B.E. 2522, Section 43, paragraph 1). If the patent is granted after year 5 has already started (substantive examination often takes several years), you must pay for year 5 through the year of grant, all together, within 60 days of the grant date (paragraph 2).
What Happens If You Pay Late
If you miss the 60-day deadline above, the law provides an additional grace period - but with a penalty:
- A 30% surcharge on the annual fee
- An additional 150 days from the end of that original 60-day deadline to pay the fee plus surcharge (Section 43, paragraph 3)
- If it's still unpaid after those 150 days, the Director-General of the DIP reports it to the Patent Committee to order revocation (paragraph 4)
- The patentee may petition the Committee within 60 days of the revocation notice, to request an extension or have the revocation rescinded, if there was genuine necessity that prevented payment within the 150-day window (paragraph 5)
A revoked patent cannot be reinstated. You would have to file a brand-new application (if the invention still meets the novelty requirement), which is protected only from its new filing date - not retroactively from the original patent.
Can You Prepay in One Lump Sum?
Yes. Patent Act B.E. 2522, Section 44 allows the patentee to prepay all annual fees in a single lump sum instead of paying year by year (THB 140,000 total for an invention patent at current rates). Worth knowing before you decide: if the annual fee schedule is later amended, or the patentee surrenders the patent, or the patent is revoked, the law explicitly states the patentee gets no refund of the amount already prepaid. Weigh your confidence that you'll use the patent for its full term before committing to a lump-sum prepayment.
Frequently Asked Questions
What happens if I never pay the annual fee?
If you miss the 60-day payment window, you owe a 30% surcharge and get an additional 150-day grace period from the end of that 60-day window. If it's still unpaid after that, the Director-General of the DIP reports it to the Patent Committee to order revocation. You may petition the Committee within 60 days of the revocation notice for an extension if there was genuine necessity - but a revoked patent cannot be reinstated; you'd have to file a brand-new application, which gets no retroactive protection from the original filing date.
Should I prepay all annual fees in one lump sum?
You can, under Section 44 of the Patent Act - a single payment instead of paying year by year. The upside is not having to track a yearly deadline. The catch: if the fee schedule changes later, or the patent is surrendered or revoked, the law states you get no refund of the prepaid amount. Weigh how confident you are that you'll keep the patent for its full term before prepaying in a lump sum.