Section 135 explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
Section 135 sets the twelve-month rule for convention applications. If a person has made a "basic application" for a patent in a convention country, and that person, or his legal representative or assignee, applies in India within twelve months after the date of the basic application, the priority date of a claim of the complete specification based on matter disclosed in the basic application is the date of the basic application. Sub-section (2) deals with cognate inventions, and sub-section (3), added in 2005, with applications under the Patent Cooperation Treaty. If you have a foreign filing and want protection in India, our patent drafting and filing team can plan the Indian filing within the period.
s.135(1): "Without prejudice to the provisions contained in section 6", if a person has a basic application in a convention country and he, or his legal representative or assignee, applies in India within twelve months after the basic application, the priority date of a claim based on matter disclosed in it is the date of the basic application. With two or more convention countries, the twelve months run from the earliest. s.135(2): one application for cognate or modified inventions, within twelve months of the earliest. s.135(3): for a PCT application designating India that claims priority from an earlier Indian application, subsections (1) and (2) apply as if that Indian application were the basic application.
Amendments to know
Sub-section (3) was inserted by the Patents (Amendment) Act, 2005 (15 of 2005), section 69, with effect from 1 January 2005, and is shown in square brackets. Sub-sections (1) and (2) have no amendment footnote. The Tribunals Reforms Act, 2021 and the Jan Vishwas (Amendment of Provisions) Act, 2023 did not change this section. The word "convention country" comes from section 133.
Sub-section (1): the twelve-month rule
"Without prejudice to the provisions contained in section 6, where a person has made an application for a patent in respect of an invention in a convention country (hereinafter referred to as the 'basic application'), and that person or the legal representative or assignee of that person makes an application under this Act for a patent within twelve months after the date on which the basic application was made, the priority date of a claim of the complete specification, being a claim based on matter disclosed in the basic application, is the date of making of the basic application."
| Element | What the text says |
|---|---|
| Starting point | An application for a patent in respect of an invention in a convention country, called the "basic application" |
| Who may file in India | That person, or his legal representative or assignee |
| Time | "within twelve months after the date on which the basic application was made" |
| Result | The priority date of a claim based on matter disclosed in the basic application is the date of making of the basic application |
Key points:
- Claim-by-claim. The priority date is that "of a claim of the complete specification, being a claim based on matter disclosed in the basic application". A claim that rests on matter not in the basic application does not take the earlier date. The text does not say what its date then is; read section 11 for that, as explained in our article on the priority dates of claims.
- "Without prejudice to section 6". The rights of persons entitled to apply under section 6 are not cut down by section 135.
- Who may file. The Indian applicant is the person who made the basic application, or his legal representative or assignee. A stranger cannot claim the priority.
- Complete specification. The Indian application must have a complete specification for the claims; section 136 requires it.
The Explanation: several convention countries
"Where applications have been made for similar protection in respect of an invention in two or more convention countries, the period of twelve months referred to in this sub-section shall be reckoned from the date on which the earlier or earliest of the said applications was made."
So filing in a second country does not restart the clock. If the first filing was in country A on 1 March and a second in country B on 1 May, the twelve months run from 1 March.
Sub-section (2): cognate inventions
"Where applications for protection have been made in one or more convention countries in respect of two or more inventions which are cognate or of which one is a modification of another, a single convention application may, subject to the provisions contained in section 10, be made in respect of those inventions at any time within twelve months from the date of the earliest of the said applications for protection."
The proviso says "the fee payable on the making of any such application shall be the same as if separate applications have been made in respect of each of the said inventions", and "the requirements of clause (b) of sub-section (1) of section 136 shall ... apply separately to the applications for protection in respect of each of the said inventions". So the single application does not save the fee, and the statement of date and country in section 136(1)(b) is made separately for each invention. The amount of the fee is "prescribed" elsewhere and is not given here. The words "subject to the provisions contained in section 10" connect the single application to the rules on specifications.
Sub-section (3): PCT applications claiming priority from India
"In case of an application filed under the Patent Cooperation Treaty designating India and claiming priority from a previously filed application in India, the provisions of sub-sections (1) and (2) shall apply as if the previously filed application were the basic application."
The proviso: "a request for examination under section 11B shall be made only for one of the applications filed in India."
Two points:
- The "basic application" here is an Indian application, not one in a convention country. Without this sub-section, sub-section (1) would speak only of a convention country.
- Only one of the Indian applications can be put forward for examination: the request under section 11B is made "only for one of the applications filed in India". See our article on section 11B.
Timeline example
| Date | Event |
|---|---|
| 1 March | Basic application filed in a convention country |
| 15 September | Applicant files in India with a complete specification, within twelve months |
| Result | Claims based on matter disclosed in the basic application take 1 March as priority date |
| Following 2 March | Twelve months have passed; a fresh Indian filing would not get the priority under section 135(1) |
The text counts "within twelve months after the date on which the basic application was made". The treatment of a last day that falls on a holiday is not given in section 135; the Rules or other provisions may deal with it.
Illustration (invented)
Kiran Electronics Pvt. Ltd. files a basic application on a battery separator in a convention country on 10 April. It files in India on 20 February of the next year with a complete specification whose claim 1 is based on matter in the basic application and whose claim 5 adds a new coating. Under section 135(1), the priority date of claim 1 is 10 April of the earlier year. Claim 5 is not based on matter disclosed in the basic application, so it does not take that date under this sub-section.
In a second case, Hari Labs makes applications in two convention countries on two related inventions, one a modification of the other. It makes a single convention application in India within twelve months of the earlier of them, under sub-section (2). It pays the fee as if it had made separate applications, and states the date and country of the basic filing for each invention separately.
What the section does not say
- It does not name any convention country or treaty.
- It does not extend the twelve months.
- It does not say how the twelve months are computed when the last day is a holiday.
- It does not list documents; section 136 and section 138 deal with those.
For a wider guide, see our post on convention applications and Paris Convention priority.
Need help with a convention filing?
The twelve-month window cannot be stretched by the text of this section. Our patent drafting and filing team can prepare the complete specification, track the dates from your earliest foreign filing and file the Indian application in time.
Key takeaways
- A convention application filed in India within twelve months of the basic application takes the basic application's date as priority date for claims based on matter disclosed in it.
- With several convention countries, the twelve months run from the earliest application.
- Cognate or modified inventions may be covered in a single application within twelve months of the earliest, at the same fee as separate applications.
- A PCT application designating India and claiming priority from an earlier Indian application is treated as if that Indian application were the basic application.
- A request for examination is made for only one of the Indian applications in that case.
Read next
- Section 136: special provisions relating to convention applications
- Section 137: multiple priorities
- Sections 133 and 134: convention countries and countries without reciprocity
- Patent Cooperation Treaty (PCT): national phase entry in India
Disclaimer: Based on the Patents Act, 1970 as amended up to the Jan Vishwas (Amendment of Provisions) Act, 2023, as consulted on 1 October 2026. Forms, fees and time limits under the Patents Rules, 2003 change from time to time and are not covered here. This article is general information, not legal advice; check the official text before acting.