Rule 13 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.
Rule 13 governs how a specification is made. Sub-rules (1) to (6), and the new sub-rule (2A) added in 2024, cover Form 2, the references a divisional application and a patent of addition must carry, how drawings are referred to, what is excluded, and the declaration of inventorship in Form 5. The title and abstract (sub-rule (7)) and the reference to the deposit of biological material (sub-rule (8)) are covered in our companion article on rule 13(7) and (8).
Every specification, provisional or complete, is made in Form 2 (rule 13(1)). A divisional specification must refer to the number of the original application; a patent of addition specification must refer to the main patent and state that the invention is an improvement or modification. Since 2024, an applicant may file one or more further applications under section 16, including from a further application (rule 13(2A)). The Form 5 inventorship declaration is due with the complete specification or within one month of its filing, if the Controller allows on Form 4.
Sub-rule (1): Form 2 for every specification
"Every specification, whether provisional or complete, shall be made in Form 2." The Second Schedule lists Form 2 as the Provisional/Complete Specification under section 10 and rule 13. The text of Form 2 is not printed in the sources used for this series, so we do not describe its entries. For the Act, see our articles on section 9 (provisional and complete specifications) and section 10 (claims, abstract and biological material), and for the choice between the two types see provisional versus complete specification.
If you are deciding whether to file a provisional specification first, our provisional patent filing service can prepare Form 2 and plan the follow-up. For a general walk-through, see our guide on how to file Form 2.
Sub-rule (2): divisional specifications
A specification in respect of a divisional application under section 16 shall contain specific reference to the number of the original application from which the divisional application is made. A divisional specification without that reference is incomplete under this sub-rule.
Sub-rule (2A): further applications (inserted in 2024)
The Patents (Amendment) Rules, 2024 inserted sub-rule (2A): "A patent applicant may, if he so desires, file one or more further applications under section 16, including in respect of an invention disclosed in the provisional or complete specification or a further application filed under section 16."
Three points arise from this text. The applicant may file one or more further applications. The invention may be one disclosed in the provisional specification or in the complete specification. And a further application can itself be the parent of another, because the rule covers an invention "disclosed in ... a further application filed under section 16". Where a further application is filed is governed by rule 4(4); see rules 3 and 4. The Act-side rule is in our article on sections 16-17, and the practice is described in our guide on divisional patent applications.
Sub-rule (3): patents of addition
A specification in respect of a patent of addition under section 54 shall contain:
- a specific reference to the number of the main patent, or of the application for the main patent, as the case may be; and
- a definite statement that the invention comprises an improvement in, or a modification of, the invention claimed in the specification of the main patent granted or applied for.
See our article on sections 54-56 and the guide on patents of addition.
Sub-rule (4): drawings
Where the invention requires explanation through drawings, they shall be prepared in accordance with rule 15 and supplied with, and referred to in detail in, the specification, including the claims, where the features illustrated in the drawings shall be followed by their reference signs in parentheses. A proviso lets an applicant adopt, in a complete specification, the drawings filed with the provisional specification, by referring to them as those left or filed with the provisional specification. Rule 15 is covered in our article on rules 14 to 16.
Sub-rule (5): irrelevant matter
Irrelevant or other matter, not necessary in the opinion of the Controller for elucidation of the invention, shall be excluded from the title, description, claims and drawings. The test is the Controller's opinion.
Sub-rule (6): declaration of inventorship in Form 5
The sub-rule says that, except in the case of an application (other than a convention application or an application filed under the Patent Cooperation Treaty designating India) which is accompanied by a complete specification, a declaration as to the inventorship shall be filed in Form 5:
- with the complete specification; or
- at any time before the expiration of one month from the date of filing of the complete specification, as the Controller may allow on an application made in Form 4.
The Explanation says that, for an application corresponding to an international application in which India is designated, the date of filing of the complete specification is reckoned from the actual date on which the corresponding application is filed in India.
| Item | Form | Period | Fee entry (First Schedule, as substituted in 2024) |
|---|---|---|---|
| Specification | Form 2 | Provisional or complete | Entries 1 and 2 |
| Declaration of inventorship | Form 5 | With the complete specification, or within one month if allowed on Form 4 | Entry 5: no fee |
| Request for extension on Form 4 | Form 4 | Per month | Entry 4(i) |
Entry 4(i) covers extension of time under rules 13(6), 80(1A) and 130 and sections 53(2) and 142(4), per month, in four columns. Form 4 as substituted in 2024 is headed "Request for extension of time or condonation of delay" and cites rule 13(6) among its authorities. Our overview of how to file Form 5 covers the filing step.
A worked example
Ishaan Robotics files a provisional specification in Form 2 for a gripping device. Twelve months later it files the complete specification, again in Form 2, and adopts the drawings of the provisional specification by referring to them as those filed with the provisional specification (rule 13(4) proviso). Because it is an ordinary application and not a convention or PCT application, whether Form 5 is needed turns on the exception in rule 13(6); if Form 5 is required, it goes in with the complete specification or within one month, as the Controller allows on Form 4.
Later, the company discovers a second invention disclosed in the complete specification. Under rule 13(2A) it may file a further application under section 16. That specification must state the number of the original application (rule 13(2)). If it also files an improvement on its granted patent, the new specification must refer to the main patent and state that the invention is an improvement or modification (rule 13(3)).
Common errors to avoid
- Omitting the original application number in a divisional specification.
- Omitting the "improvement or modification" statement in a patent of addition.
- Leaving reference signs out of the claims when drawings are used.
- Missing the Form 5 date, one month from filing the complete specification, unless extended on Form 4.
- Adding material not needed to explain the invention.
Need help with your specification?
A specification fixes the scope of what you can later enforce. If you would like a specification and its Form 5 and drawings prepared and checked against rule 13, speak to our team about provisional patent filing.
Key takeaways
- Every specification, provisional or complete, is in Form 2.
- Divisional and addition specifications carry mandatory references.
- Rule 13(2A), inserted in 2024, allows one or more further applications, including from a further application.
- Drawings are referred to in detail, with reference signs in the claims.
- Form 5 follows the complete specification within one month, extendable on Form 4 where the rule allows.
- Check amendments after the Second Amendment Rules, 2024.
Read next
- Rule 12: statement and undertaking regarding foreign applications
- Rule 13(7) and (8): abstract, title and deposit of biological material
- Rules 14 to 16: amendments to specifications, drawings and models
- Divisional patent application: when and how to file
Disclaimer: Based on the Patents Rules, 2003 as consolidated up to 21 September 2021 and as amended by the Patents (Amendment) Rules, 2024 and the Patents (Second Amendment) Rules, 2024, as consulted on 2 October 2026. Later amendment rules, forms and fees should be checked in their current form. This article is general information, not legal advice; check the official text before acting.