PCT National Phase in India: the 31-Month Deadline (Calculator)

How-To · Patents · Last verified October 2026

Updated for 2026 · Claw Editorial

If you miss the Indian national phase date for a PCT application, the application is lost in India, and there is no reinstatement to rescue it. The date is 31 months from the earliest priority date, and counting it wrongly by even one day is the most expensive mistake in cross-border patent filing. This guide shows how to count the 31 months, what to file by then, and how to set up reminders so the date never slips. Last verified October 2026.

01Why this deadline is unforgiving

The national phase deadline in India cannot be extended, and a missed date cannot be revived. That one fact is what makes it dangerous.

The clock starts long before you think about India

The 31 months run from the earliest priority date, not from the date you filed the PCT application, and not from the date the international search report arrived. By the time an Indian agent is instructed, a year or more may already be gone. Many teams count from the wrong date.

Other countries are more forgiving

Some offices allow late entry or restore rights if the delay was unintentional. India does not apply that approach at the national phase. WIPO lists the time limit for India as 31 months, and Indian practice treats it as final. See the note on reinstatement below.

The cost of a miss is the whole Indian patent

There is no partial loss. If the entry is not made in time, the Indian filing right from that international application ends. The invention may then be open to others in India.

In India the PCT national phase date is not a target. It is a cliff: 31 months from the earliest priority date, with no reinstatement.

02The rule in one line

The Indian national phase must be entered within 31 months from the priority date, under Rule 20(4)(i) of the Patents Rules 2003.

• 31 months from the earliest priority date. WIPO’s time limits table lists India at 31 months for entry under both Chapter I and Chapter II of the PCT.
• No reinstatement. India has reserved against PCT Rule 49.6, so the “unintentional delay” route that other offices offer is not available. Indian courts have looked at this reservation.
• The request for examination also falls at 31 months. For national phase applications, the request for examination (Form 18) is due by the same 31 month point.

Treat 31 months as the single date for three things: entry, the examination request, and the cut-off for any claim that you are still “in time”.

03How to calculate the date

To find the deadline, take the earliest priority date and add 31 calendar months. Follow these steps.

1. Find the earliest priority date. This is the filing date of the first application (for example, an Indian provisional or a foreign first filing) that the PCT application claims. It is printed on the PCT request and on the front page of the published international application.
2. Do not use the PCT filing date. If a priority is claimed, the PCT filing date is usually later. Counting from it will give you a date that is too late.
3. Add 31 months. Move the month forward 31 times. Keep the same day number. Add 2 years and 7 months: that is 31 months.
4. Handle short months. If the target month does not have that day, use the last day of that month. A priority date of 31 July plus 31 months lands in February, so the safe date is the last day of February.
5. Look at the day of the week. If the date is a weekend or holiday, do not assume you get extra time. File early. Treat any extension for office closure as unconfirmed.
6. Set your internal deadline earlier. A sensible practice is to treat the day 30 days before as the real deadline, with a final check 10 days before.

04Worked examples (calculator table)

The table below shows how the count works. It is an illustration of the arithmetic, not legal advice. Always check the dates against the official PCT record.

Always confirm the final date a second time, by a different person or tool, before it goes into a docket. Many national phase errors are simple counting errors made once and never rechecked.

05What to file by 31 months

At or before the 31 month date, an application corresponding to the international application must be filed with the Indian Patent Office, using Form 1.

Core filing items

• Form 1 with the national phase details and the fee.
• Specification and claims in English, or an English translation if the international application was published in another language.
• Request for examination (Form 18), due within the same 31 month window for national phase applications.
• Power of authority (Form 26) if an agent files. It is often permitted shortly after filing, but confirm the current practice.
• Foreign filing information (Form 3) and related declarations, where required.

Fees and forms change from time to time. Always read the current schedule on the IP India website before filing.

06Common mistakes that cost the application

• Counting from the PCT filing date. If there is a priority claim, count from the earliest priority date.
• Counting 30 months. Many countries use 30 months. India uses 31. A team used to the 30 month rule may relax and miss the Indian requirement, or the reverse.
• Assuming a late filing can be saved. India does not restore rights under PCT Rule 49.6. Do not tell a client that a petition will fix a missed date.
• Forgetting the examination request. The RFE also falls at 31 months. Entry without it can leave the application exposed.
• Waiting for the end of the month. The portal can be slow near deadlines, payments can fail, and a weekend can hide a problem. File early.
• Not rechecking priority changes. If the priority claim is corrected or withdrawn, the date can move.

For other Indian IP dates in one place, see our master table of Indian IP statutory deadlines.

07Keeping the date safe: a simple system

A deadline you cannot miss needs two independent checks and a reminder that reaches a person, not just a calendar.

• Two people compute the date separately and compare.
• Add three reminders: 90 days, 30 days and 10 days before the final date.
• Record the priority date source (the PCT request or published front page) next to the date in the docket.
• Check the status after filing. Look up the application on the IP India public search to confirm that the national phase entry is recorded.

If you manage patents alongside litigation, you may also want to watch court matters tied to the same family. Tools that watch cases can be reached through APIs, and our guide on using a litigation monitoring API covers that side of the work.

08Where Claw fits

Claw is an all-in-one legaltech platform for Indian advocates, law firms, and corporate legal teams, combining AI-based case search, an AI legal assistant (Legal GPT), case management, and compliance automation across all Indian courts and tribunals.

Counting the 31 months is registry work. How Indian courts have treated a missed national phase date, and the reservation against PCT Rule 49.6, lives in judgments. Claw tracks cases, orders and hearings across 9,102 courts, benches and forums, with 30 crore+ judgments and results in under 5 seconds, covering the Supreme Court from 1950 and the High Courts from 1990. So you can read how the High Court IP divisions have decided such matters.

Claw does not use customer documents to train AI models. Create a FREE Claw account to follow these patent matters by party or advocate. To search the wider body of law, see case search across Indian courts.

09Sources and further reading

Check every date and form against the primary sources:

• WIPO, PCT time limits for entering the national phase: wipo.int/pct/en/texts/time_limits.html
• Indian Patent Office (forms, fees, rules): ipindia.gov.in
• IP India public search: ipindiaservices.gov.in/PublicSearch
• Claw: clawlaw.in

Last verified October 2026. This guide is general information and not legal advice. Confirm the current Patents Rules and fees before filing.

10Frequently asked questions