This is a practical manual for staff managing Thai (TH) patent annuities. It covers the anchor date and deadline calculation, the grace period and surcharge, what to do when a right lapses, and the lump-sum prepayment option, organized around the items you need to check in your docket. It is deadline-management guidance for practitioners, not legal advice.
1. At a Glance
- System type
- Annual annuity system (years 5-20)
- Anchor date
- Filing date
- Deadline method
- Within 60 days from the start date of each annuity year (anniversary of the filing date)
- Start of payment obligation
- From the 5th year, and only after grant If grant occurs after the 5th year, all accrued annuities are due in a lump sum within 60 days of the grant date
- Term
- Filing date + 20 years
- Grace period
- 120 days (not 6 months) + 30%
- Restoration
- Effectively none Only a 60-day opposition procedure after a notice of cancellation exists
- Reductions
- None
- Lump-sum prepayment
- THB 140,000 for all remaining years in a lump sum
- Management risk level
- High The grace period is short and relief is narrow, so reminder lead times must be moved up
2. Anchor Date and Deadline Calculation
Thailand uses the filing date as the anchor date. The anniversary of the filing date, not the grant date, is the start date of each annuity year. The deadline is not that anniversary itself but a window of 60 days from the anniversary.
- Anchor date: filing date
- Deadline method: within 60 days from the start date of each annuity year (anniversary of the filing date)
- Term: filing date + 20 years
Here is an actual calculation example. For a case with a filing date of 2020-06-15 and a grant date of 2023-03-10, the annuity deadlines are calculated as follows.
| Annuity year | Deadline |
|---|---|
| Year 5 | 2024-06-15 |
| Year 6 | 2025-06-15 |
| Year 7 | 2026-06-15 |
| Year 8 | 2027-06-15 |
| Year 9 | 2028-06-15 |
| Year 10 | 2029-06-15 |
| Year 11 | 2030-06-15 |
| Year 12 | 2031-06-15 |
This case generates a total of 16 payment events, from year 5 through year 20. In other words, a single filing date is the basis for 16 deadlines. If the filing date field is empty or entered incorrectly, all 16 will be wrong.
3. Start of the Payment Obligation
Annuity years are counted from the filing date, but the payment obligation arises only after grant. Annuities apply from the 5th year onward; no annuities are paid while the application is still pending.
- Applicable annuity years: year 5 through year 20
- No annuity payment obligation while the application is pending (under examination)
- If grant occurs after the 5th year: all accrued annuities must be paid in a lump sum within 60 days of the grant date
4. Grace Period and Surcharge
Thailand's grace period is 120 days. This differs from the 6-month grace period common in other countries, so you must not simply copy another calendar. Payment during the grace period carries a 30% surcharge.
| Category | Period | Surcharge |
|---|---|---|
| Regular payment window | Within 60 days from the start date of each annuity year (anniversary of the filing date) | None |
| Grace period | 120 days | 30% |
5. Lapse and Restoration
The operational implication is clear. For Thai cases, it is better to classify entry into the grace period itself as an incident rather than a normal flow, and to flag it separately in the docket status field. We recommend a rule that escalates cases with delayed instructions before the grace period begins.
- First reminder: request instructions before the regular payment window opens (before the filing anniversary)
- Second reminder: escalate cases with no response within the regular payment window (anniversary + 60 days)
- Third reminder: treat entry into the 120-day grace period as an incident and confirm with the client immediately
6. Reductions
There is no fee reduction system for Thai patent annuities. There is no rate differentiation by size or entity type (individual, SME, university, etc.), so quotes and invoices are calculated at the full amount.
- Reductions: none
- Rate categories by entity size: none
- Accordingly, there is also no risk to the right arising from an erroneous claim (an improper reduction request)
7. Prepayment and Lump-Sum Payment
Thailand expressly provides an option to pay all remaining years in a lump sum. The amount is THB 140,000, which produces a saving compared with the sum of the individual yearly amounts.
| Category | Amount (THB) |
|---|---|
| Lump-sum payment for all remaining years | 140,000 |
| Sum of yearly amounts (years 5-20) | 152,000 |
8. Official Fees
The following are the confirmed reference annuity amounts. The currency is THB and no conversion has been made.
| Item | Amount (THB) | Notes |
|---|---|---|
| Year 5 | 1,000 | Annuities begin |
| Year 10 | 4,000 | |
| Year 15 | 10,000 | |
| Year 20 | 25,000 | |
| Total for years 5-20 | 152,000 | |
| Lump sum for all remaining years | 140,000 | Lump-sum payment option |
| Grace period surcharge | 30% | When paid within the 120-day grace period |
9. Management Checklist
Items to check in the case docket
- Filing date: this is the sole anchor date for Thai annuities. If this field is empty, every deadline from year 5 to year 20 will be wrong. Cases that have only a grant date and no filing date should be corrected immediately.
- Grant date: needed to determine when the payment obligation starts and to calculate the lump-sum deadline (grant date + 60 days) where grant was delayed.
- Last annuity year paid to date: the basis for calculating the next deadline.
- Whether a lump-sum payment was made: for cases paid in a lump sum for all remaining years (THB 140,000), no further annuity tasks are generated.
- Term expiry date: filing date + 20 years. Check that no annuity tasks remain after expiry.
- Local agent and payment route: record, case by case, the lead time required for remittance and confirmation of receipt.
Payment cycle sequence
- Confirm the filing anniversary (the start date of the annuity year) and request the client's instructions on maintenance before that date.
- Confirm whether the patent has been granted. If not granted, no payment obligation arises for this cycle.
- For cases granted after the 5th year, calculate all accrued annuities together with a deadline of grant date + 60 days.
- Fix the annuity amount. For the range of years 12-20, ⚠️ verify the individual amounts against the original fee schedule before invoicing.
- Complete payment within the regular payment window (anniversary + 60 days).
- Obtain proof of payment, update the last annuity year paid in the docket, and generate the next cycle's deadline.
- Cases that pass 60 days unpaid are treated as having entered the grace period (120 days + 30%) and are escalated immediately. Since there is effectively no restoration system, reach a conclusion at this stage.
- For cases that opted for lump-sum payment, close out subsequent annuity reminders once payment is confirmed.
Sources, cut-off date and disclaimer
This manual is based on iphere's August 2026 survey of country-by-country overseas maintenance rules, together with values produced by the deadline engine that runs on those same rules. Official fees and deadline rules change by office notice, so please confirm against the official source and your local agent before any actual payment or filing.