CRI Guidelines 2025 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.
Paragraph 4.5 of the CRI Guidelines 2025 sets the approach for all four limbs of section 3(k): look at the substance of the claim, taken as a whole. Paragraph 4.5.1 then applies it to the first limb, mathematical methods, with a three-step assessment and two hypothetical examples.
The examiner must judge the substance of the claim as a whole, whatever its form (para 4.5). A claim is a mathematical method if its solution lies in abstract mathematical processing that only produces an output; it is not excluded if the mathematics is part of a larger technical process (para 4.5.1.1). A formula in a claim does not by itself make it a mathematical method (para 4.5.1). The Guidelines are the Patent Office's guidance and do not have the force of law; the Patents Act, 1970 and the Patents Rules, 2003 as now in force prevail.
The Office revises its guidelines, so check the current version on ipindia.gov.in. For the definitions and the four limbs see the opening article on the CRI Guidelines. If a mathematical method objection is already before you, a patent objection reply built on the steps below is the usual response.
Paragraph 4.5: substance over form
Alongside testing the invention under section 2(1)(j), (ja) and (ac), the examiner must decide whether it is excluded under section 3. Paragraph 4.5 makes three points.
- Computer programmes are often claimed as algorithms, method claims or system claims with "means" standing for flow chart steps.
- The focus is on the underlying substance, not the form of the claim.
- If a claim in any form (method or process, apparatus or system, computer program product or computer readable medium) falls within an excluded category, it is not patentable; but if the claim as a whole does not fall within one, the patent "should not be denied".
That last point matters for the applicant. The Guidelines expressly tell the examiner not to refuse a claim merely because it contains software or mathematics.
What counts as a mathematical method (paragraph 4.5.1)
The Guidelines describe mathematical methods as a particular example of the principle that purely abstract or intellectual methods are not patentable. They list methods of calculation, formulation of equations and finding roots, and "all other similar acts of mental skill". They add that mere manipulation of an abstract idea, or solving a purely mathematical problem, without specifying a practical application also attracts the exclusion.
Two clarifications favour the applicant.
- The mere presence of a mathematical formula in a claim, used to specify the scope sought, may not make it a mathematical method claim.
- The exclusion may not apply to inventions that include formulae and result in systems for encoding, reducing noise in communications or electrical or electronic systems, or encrypting and decrypting electronic communications.
The three-step assessment (paragraph 4.5.1.1)
| Step | What the examiner does | What the applicant should have ready |
|---|---|---|
| 1. Construe the substance | Understand the claimed invention in its entirety, to capture its primary objective and the solution it offers | A description that states the technical objective in plain terms |
| 2. Determine the nature of the solution | Ask: (a) does the solution in essence lie in abstract mathematical processing, showing only operations on equations, statistical models or computations to define an output; or (b) is the mathematics not the primary objective but part of a larger technical process, contributing to a broader technical objective | Claim features showing what the output is used for |
| 3. Conclude | If step 2(a): the claim falls within the mathematical method exclusion. If step 2(b): it does not | Argument that matches the claim to 2(b) |
The deciding question is therefore what the mathematics is for. If the calculated number is the end product, the claim fails. If the number drives something technical, the claim has a good chance.
The Guidelines' first example: a compatibility index
The Guidelines' Example 1 is a data processing system with a processor, a memory and a module that takes two datasets, applies a predefined formula and outputs a compatibility index. The Office's reasoning is that the core objective is applying the formula, the index is the direct result of the computation, and the system is merely a tool for the calculation. The invention does not contribute to a larger technical process, so it falls under step 2(a) and is excluded.
The lesson is that reciting a processor and a memory does not change the substance. A claim whose only content is "apply this formula and output the result" is excluded even in system form.
The Guidelines' second example: a robotic arm
Example 2 is a method of controlling a robotic arm to put its end effector at a target position. The method takes target coordinates, calculates joint angles by inverse kinematics, and generates control signals to move the joints, using sensor feedback. The Office finds that the calculation is "a necessary intermediate step", the method starts with a practical input and ends with a physical action, and the joint angles drive actuators. Step 2(b) is met, so the claim is not excluded.
The lesson is the reverse. The same kind of mathematics, placed inside a process that ends in physical control, is outside the exclusion.
How the objection is usually framed, and how to answer it
| Objection | Answer |
|---|---|
| "The claim is a mathematical method as it recites equations and computations" | Show that a formula in a claim does not by itself make it excluded (para 4.5.1); identify the larger technical process the calculation serves |
| "The output is only a number or index" | Identify what the output is used for in the claim: a control signal, a stored record that changes system operation, an encoded signal |
| "The claim is mathematical in substance although it names hardware" | Show that the hardware does more than carry out the calculation, and that the final step produces a technical result |
Annexure I contains many more mathematical method examples; our article on Annexure I Examples 21 to 34 sorts them into claims that pass and claims that fail.
A worked example (invented)
Kavach Systems files a claim to a method of reducing noise in a sensor signal by applying a filter defined by an equation, and then outputting a filtered signal to a controller. The examiner objects under section 3(k) as a mathematical method. Kavach replies that the claim does not stop at the equation; the filtered signal is fed to the controller, which changes the operation of a machine, and the description states the noise problem in the physical system. This follows the pattern of step 2(b) and the express reference in paragraph 4.5.1 to systems that reduce noise in communication or electronic systems.
Common lapses
- Describing the invention only as "calculating X" without saying what X is for.
- Drafting the final claim step as "outputting the result" when the description shows a technical use.
- Relying on hardware wording without showing a technical function for it.
- Ignoring the second clarification in paragraph 4.5.1 when the invention is an encoding or encryption system.
Need help with a section 3(k) objection on a mathematical method?
The reply should identify the technical process the calculation serves and tie it to the claim wording. We can review the claims against the three steps and prepare the response. See patent objection reply, and for the next limb of section 3(k) read the business method exclusion.
Key takeaways
- The examiner judges the substance of the claim as a whole, in any form.
- A solution that lies in abstract mathematical processing is excluded.
- Mathematics that is part of a larger technical process is not excluded.
- A formula in a claim does not by itself make it a mathematical method.
- Encoding, noise reduction and encryption systems are named as areas where the exclusion may not apply.
Read next
- CRI Guidelines 2025: scope, terms and the four limbs of section 3(k)
- CRI Guidelines 2025, paragraph 4.5.2: the business method exclusion
- CRI Guidelines 2025, Annexure I: Examples 21 to 34
- Software Patents in India: Can Software Be Patented
Disclaimer: Based on the manuals and guidelines published by the Office of the Controller General of Patents, Designs and Trade Marks that are named in the article, as consulted on 4 October 2026. They are guidance and do not have the force of law; the Patents Act, 1970 and the Patents Rules, 2003 as amended (including the 2024 amendment rules) prevail, and the current versions on ipindia.gov.in should be checked. This article is general information, not legal advice; check the official text before acting.