Patent Deadline Calculator
The filing date of your first application for the invention, anywhere.
Statutory periods only. Holidays, extensions and restoration are not applied. Confirm every date with your patent agent.
Enter a priority date
The calculator lists the Indian, PCT and convention deadlines that run from it, with the legal basis for each.
How the patent deadline calculator works
Enter the priority date
The filing date of the first application for the invention, in India or elsewhere. Every period below runs from it.
Say where you filed first
An Indian provisional adds the 12-month complete specification deadline; a foreign first filing adds the Indian convention deadline instead.
Review, save and confirm
Each date shows its legal basis and source. Download the dates to your calendar and send them to us to confirm against your file.
How each deadline is counted
The periods the calculator applies, with their legal basis. Calendar months are counted to the same day; where that day does not exist, the last day of the month is used.
| Deadline | Counted from priority | Applies to | Legal basis |
|---|---|---|---|
| Earliest date to file abroad without a foreign filing licence | 6 weeks | Indian provisional, Indian complete | Patents Act, s. 39 |
| File the complete specification | 12 months | Indian provisional | Patents Act, s. 9(1) |
| Convention applications in other countries | 12 months | Indian provisional, Indian complete | Paris Convention, art. 4; Patents Act, s. 135 |
| Indian convention application claiming the foreign priority | 12 months | Foreign first filing | Patents Act, s. 135 |
| PCT international application claiming priority | 12 months | Indian provisional, Indian complete, Foreign first filing | PCT art. 8; Paris Convention, art. 4 |
| Publication of the Indian application | 18 months | Indian provisional, Indian complete, Foreign first filing | Patents Act, s. 11A; Patents Rules, r. 24 |
| Request for examination in India (Form 18) | 31 months | Indian provisional, Indian complete, Foreign first filing | Patents Rules, r. 24B(1)(i), as amended in 2024 |
| PCT national phase: USA and other 30-month offices | 30 months | Indian provisional, Indian complete, Foreign first filing | PCT art. 22 and 39 |
| PCT national phase: India and the EPO | 31 months | Indian provisional, Indian complete, Foreign first filing | Patents Rules, r. 20(4)(i); EPC r. 159 |
| First renewal fee (3rd year) | 24 months from the Indian filing date | Indian provisional, Indian complete | Patents Act, s. 53 and s. 142(4); Patents Rules, r. 80 |
Applications filed in India before 15 March 2024 keep the earlier 48-month period for the request for examination.
Frequently asked questions
What is a priority date?
The filing date of the first application for an invention. Later applications abroad, filed within 12 months under the Paris Convention or through the PCT, can claim it, so prior art is judged as at that date.
When must the complete specification be filed after a provisional?
Within 12 months of the provisional application under section 9(1) of the Patents Act, 1970. The period cannot be extended; if it is missed, the application is treated as abandoned.
What is the deadline for the request for examination in India?
For applications filed on or after 15 March 2024, Form 18 must be filed within 31 months of the priority date or filing date, whichever is earlier, under the Patents (Amendment) Rules, 2024. Earlier applications keep 48 months.
When is the PCT national phase deadline in India?
Thirty-one months from the priority date. Most other offices, including the USPTO, apply 30 months; the EPO applies 31. Our guide to the PCT process from India explains the steps.
Why does the calculator show a date six weeks after filing?
Section 39 bars persons resident in India from filing abroad until six weeks after the Indian application, unless they hold a foreign filing licence. See our foreign filing licence guide.
Is the .ics download private?
Yes. The calendar file is created in your browser from the date you entered; nothing is sent to our servers unless you choose to send us an enquiry.
Official sources
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Send your result and a line about your business. A registered agent confirms it in writing within one working day.