Divisional Patent Applications in Canada: What Inventors Need to Know
If you’re filing a patent application in Canada and your invention includes more than one innovative idea, you may need to split your application. This is where divisional patent applications come in. In this guide, we explain what divisionals are, why they matter, and how to use them wisely—especially under Canada’s examination system.
What Is a Divisional Patent Application?
A divisional patent application is a new application that’s carved out from an earlier one (called the “parent”). It’s used when your original patent application describes more than one invention. Each divisional is treated as a separate application, but it keeps the same filing date and/or priority date as the parent.
Key Facts:
- Same filing & priority date: Divisionals inherit the parent’s filing and priority dates.
- Separate examination: Each divisional is reviewed independently by the Canadian Intellectual Property Office (CIPO).
- Same expiry: The 20-year patent term is still counted from the parent’s filing date.
- Separate fees: You’ll pay new filing, examination and maintenance fees for each divisional.
Why Canada Requires One Invention Per Patent
Canadian law follows a principle called unity of invention. This means your patent claims must focus on a single inventive concept.
If your claims cover multiple unrelated inventions, the Examiner at CIPO Examining your application may issue a unity objection, asking you to choose one invention to pursue in the parent application.
You can also file a divisional application on a voluntary basis. This option might be considered when your original application describes a second invention that wasn’t claimed, and you want to protect it separately.
You can then file a divisional for the other invention(s)—but only before the parent patent is granted.
When Should You File a Divisional?
There are two main scenarios:
1. Forced Divisional (after direction by Commissioner)
- CIPO tells you to limit your claims to one invention.
- You file a divisional for the other invention(s).
- This approach reduces the risk of double patenting issues.
2. Voluntary Divisional
- You choose to file a divisional without a unity objection.
- Filing a divisional after a unity objection from an Examiner might still be considered voluntary. It is best to have the Commissioner force division.
- Voluntary division exposes the issued patents to invalidity for double patenting.
- Recommended only when necessary and done carefully.
Important: You must file a divisional before the parent application is granted or irretrievably abandoned.
Pros and Cons of Filing a Divisional
Pros and Cons of Filing a Divisional
Benefit |
Risk |
|---|---|
| Broader protection: Secure patents for multiple inventions from one disclosure. | Extra cost: Each divisional has its own fees and maintenance requirements. |
| Preserves priority: Keeps the original filing and/or priority date. | Double patenting: Divisional application might not succeed or issued patents may be invalidated if claims overlap too closely. |
| Flexible strategy: Tailor claims and manage patents independently. | No term extension: All patents expire at the same time. |
| Focused claims: Easier enforcement and licensing. | Complexity: More applications mean more admin and coordination. |
Best Practices for Filing Divisionals in Canada
- If the original application hasn’t been filed, consider filing separate applications each with their own distinct set of claims for one invention only. This reduces the risk of double patenting and of having to navigate Canada’s “one invention per patent” requirement.
- If your application claims more than one invention, consider waiting for or provoking a unity objection from the Examiner before filing a divisional.
- If the Examiner raises a unity objection, try to have the decision brought directly before the Commissioner to force limitation of the claims to one invention.
- File divisional applications before grant and ideally before paying the final fee on the parent.
- Avoid overlapping claims: Draft carefully to prevent double patenting.
- Plan for costs: Each divisional has its own filing and examination fees. Maintenance fees on divisionals start from the original application filing date.
- Consult a patent agent: Strategic advice can save time and money.
Final Takeaway
Divisional patent applications are a powerful tool for Canadian inventors—but they must be used wisely. Whether you’re responding to a unity objection or proactively protecting multiple inventions, timing and strategy are key. Done right, divisionals can be a useful tool to help you build a strong patent portfolio.
If you’re unsure whether to file a divisional, speak with a registered Canadian patent agent. They can guide you through the process and help you avoid costly mistakes.
For more trademark tips and IP insights, visit our Knowledge Center for practical resources tailored to Canadian businesses.
Updated September 2025
