Section 11 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 11 says that every claim of a complete specification has its own priority date, and then sets out how that date is worked out. The priority date matters because novelty and prior art are tested against it. The usual answer is the date on which the matter in the claim was first fairly disclosed in a filing, and if there is no earlier filing, the date of filing of the complete specification. Planning a provisional patent filing is largely a question of how this section will treat the claims that follow.
Each claim has its own priority date (11(1)). If a claim is fairly based on matter disclosed in a provisional specification, its priority date is that filing date (11(2)). Where several earlier applications are involved the date is the date of the application where the matter was first disclosed, or the later one if the claim draws on two (11(3)); a complete specification filed within twelve months of an earlier Indian application takes that application's date (11(3A)). A claim with several possible dates takes the earliest (11(5)). Otherwise the date is the filing date of the complete specification (11(6)).
Section 11(1): one date per claim
"There shall be a priority date for each claim of a complete specification."
The priority date belongs to the claim, not to the specification as a whole. Two claims in one specification can have different priority dates, for instance where one is covered by a provisional specification and another is for something added later.
Section 11(2): single application with a provisional specification
Where a complete specification is filed in pursuance of a single application accompanied by a provisional specification, or by a specification treated as provisional under section 9(3), and the claim "is fairly based on the matter disclosed" in it, "the priority date of that claim shall be the date of the filing of the relevant specification". Two conditions: (i) there is a provisional specification (or one treated as provisional under section 9(3)), and (ii) the claim is "fairly based on the matter disclosed" in it. If both are met, the priority date is the filing date of that specification. If the claim goes beyond what the provisional disclosed, this sub-section does not give it the earlier date. See section 9 for the provisional and complete route.
Example. Helio Looms, a fictional company, files a provisional specification on 5 January describing a loom with a self-tensioning beam. It files the complete specification on 20 November (within twelve months). Claim 1 (the self-tensioning beam) is fairly based on the provisional, so its priority date is 5 January. Claim 6 covers a new yarn guide that was invented in August and is not in the provisional. Claim 6 does not get the January date under sub-section (2); on the text, it falls to the general rule in sub-section (6) and takes 20 November.
Section 11(3): two or more earlier applications
Where one complete specification follows two or more applications with provisional specifications (see section 9(2)), a claim fairly based on matter in one of them takes that application's filing date (clause (a)); a claim based partly in one and partly in another takes "the date of the filing of the application accompanied by the specification of the later date" (clause (b)).
Section 11(3A): a previously filed Indian application
"Where a complete specification based on a previously filed application in India has been filed within twelve months from the date of that application and the claim is fairly based on the matter disclosed in the previously filed application, the priority date of that claim shall be the date of the previously filed application in which the matter was first disclosed."
This sub-section was inserted by the 2005 Amendment Act, with effect from 1-1-2005. It covers a complete specification based on an earlier Indian application filed within twelve months. The period is printed in the sub-section, and the earlier application need not be a provisional specification in the sense of (2).
Section 11(4): divisional applications
For a further (divisional) application under section 16(1), a claim fairly based on matter in any earlier specification, provisional or complete, takes the filing date of the specification "in which the matter was first disclosed". We cover division in our article on sections 16 and 17.
Section 11(5): the earliest date wins
Where a claim would, under the foregoing provisions, "have two or more priority dates, the priority date of that claim shall be the earlier or earliest of those dates."
Drafting note. Sub-section (3)(b) gives the later date for a claim drawing partly on two specifications, while (5) gives the earliest where a claim would otherwise have several dates. The text does not say how the two interact beyond what is printed, and we do not add to it.
Section 11(6): the default rule
"In any case to which sub-sections (2), (3), (3A), (4) and (5) do not apply, the priority date of a claim shall, subject to the provisions of section 137, be the date of filing of the complete specification."
If nothing earlier applies, the filing date of the complete specification is the priority date. The rule is "subject to the provisions of section 137", which deals with multiple priorities for convention applications and which we cover later in this series; see also convention applications and Paris Convention priority.
Section 11(7): post-dating and ante-dating
So if an application was post-dated (sections 9 and 17) or ante-dated (section 16), the dates used in this section are the altered dates.
Section 11(8): publication or use after the priority date
A claim "shall not be invalid by reason only of" (a) publication or use of the invention on or after its priority date, or (b) the grant of another patent claiming the same invention with the same or a later priority date. This protects a claim against later events. It says "by reason only of"; the sub-section does not say that nothing else can invalidate the claim.
The rules at a glance
| Sub-section | Situation | Priority date of the claim |
|---|---|---|
| 11(2) | Single application with provisional; claim fairly based on it | Filing date of that specification |
| 11(3)(a) | Several provisional applications; claim based on one | Date of the application with that specification |
| 11(3)(b) | Claim based partly on two | Date of the later application |
| 11(3A) | Complete specification within twelve months of earlier Indian application; claim fairly based on it | Date of earlier application where matter was first disclosed |
| 11(4) | Further application under section 16(1) | Date of earlier specification where matter was first disclosed |
| 11(5) | Two or more dates | Earlier or earliest |
| 11(6) | None of the above | Filing date of complete specification, subject to section 137 |
Need help with ...?
Because each claim carries its own date, how you split disclosures between a provisional and a complete specification changes the outcome. We can help you plan the sequence, starting with a provisional patent filing. If you are weighing a convention route as well, see our guide to types of patent applications.
Key takeaways
- Each claim has its own priority date.
- A claim fairly based on matter in a provisional takes the filing date of that provisional.
- A complete specification filed within twelve months of a previous Indian application takes that application's date for claims fairly based on it (11(3A)).
- Where a claim has two or more dates, the earliest applies (11(5)).
- The default is the filing date of the complete specification, subject to section 137.
- Post-dating or ante-dating changes the dates used.
Read next
- Section 11A: publication of applications
- Section 16 and 17: division and dating of application
- Section 9: provisional and complete specifications
- Provisional vs complete patent specification
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.