Every application that reaches the Indian Patent Office is one of five kinds, and the kind determines the priority date it gets, the deadlines that attach to it, and in one case how long the patent lasts. Choosing wrongly is rarely fatal, but it is often expensive.
Quick reference
| Type | What it is | Key deadline |
|---|---|---|
| Ordinary | A first filing in India, provisional or complete | Complete within 12 months of a provisional |
| Convention | Claims priority from a foreign filing | Within 12 months of that filing |
| PCT national phase | Entry from an international application | 31 months from priority |
| Divisional | Carves a second invention out of a pending application | Before the parent is granted |
| Patent of addition | Protects an improvement to an existing invention | Any time the main patent is alive |
Ordinary application
The plain case: an application filed in India with no earlier filing anywhere to claim priority from. It can be filed with a provisional specification, which fixes the date and buys twelve months to file the complete specification, or with a complete one from the outset.
The priority date is the Indian filing date, and it is this filing that a resident applicant needs to have made — and to have waited six weeks after — before filing the same invention abroad.
Convention application
An application that claims priority from an earlier filing in a country that is party to the Paris Convention or the World Trade Organisation, which is nearly every country. It must be filed within twelve months of that earlier filing, and it gets the earlier filing’s date for everything the earlier filing disclosed.
A convention application must be filed with a complete specification; provisional filings are not available on this route. A certified copy of the priority document is required, with a translation if it is not in English.
The twelve months is a hard limit. India does not offer restoration of priority for a late convention filing, so an applicant who misses it can still file, but only with the Indian filing date, and only if nothing has been published in the meantime.
PCT national phase
An international application under the Patent Cooperation Treaty that designates India enters the Indian system within thirty-one months of the earliest priority date, by filing the international application as published, in English, with the fee. It is examined like any other application, but with two peculiarities: nothing can be amended at the point of entry except by deleting claims, and — for entries since March 2024 — the request for examination is due on the same day.
The route has its own guide, because the deadline is the least forgiving in Indian practice.
Divisional application
An application can only claim one invention, or a group of inventions linked by a single inventive concept. Where an application contains more than that — either because the applicant realises it, or because the examiner objects — the surplus can be carved out into a divisional application, which keeps the parent’s priority date.
Two rules govern it. The divisional must be filed before the parent is granted — a divisional filed after grant is refused, as the Delhi High Court confirmed in 2024. And it must claim subject matter that is distinct from what the parent claims; the same invention cannot be pursued twice.
The 2024 Rules settled a question that had produced years of inconsistent decisions: a divisional may be based on what is disclosed in the parent’s provisional or complete specification, whether or not the parent’s claims covered it, and a divisional may itself be divided. The earlier practice of refusing divisionals for subject matter that was described but not claimed has gone.
Divisionals are examined on their own request, and pay their own fees, but are treated as filed on the parent’s date.
Patent of addition
An applicant or patentee who improves or modifies an invention already the subject of an application or patent can protect the improvement as a patent of addition, rather than as a fresh patent.
The attraction is that a patent of addition cannot be attacked for lack of inventive step over the main invention — the improvement need be new, but need not be inventive relative to what the same applicant already disclosed. And it carries no renewal fees of its own.
The cost is term. A patent of addition expires with the main patent, however late in the main patent’s life it was granted. It cannot be granted before the main patent is, and it cannot be enforced independently unless the main patent is revoked — in which case it can be converted into an independent patent for the remainder of the term, at which point renewal fees become payable as if it had always stood alone.
It suits a genuine incremental improvement to a product the applicant is already protecting. It does not suit an improvement that is itself inventive and might outlast the original — that should be a fresh application.
Choosing
For a first filing with no foreign counterpart: ordinary, usually starting provisional if the invention is still moving. For an invention already filed abroad: convention within twelve months, or PCT if the applicant wants to defer national decisions to thirty-one months. For a second invention found in a pending file: divisional, before grant. For an improvement to something already protected: patent of addition if it is not independently inventive, a fresh application if it is.
Frequently asked questions
What is a convention application in India? An application claiming priority from an earlier filing in a Paris Convention or WTO country, filed within twelve months of that filing with a complete specification and a certified copy of the priority document. It takes the earlier filing’s date for what that filing disclosed.
When must a divisional application be filed in India? Before the parent application is granted. A divisional filed after grant is refused. It must claim subject matter distinct from the parent’s claims and keeps the parent’s priority date.
Can a divisional be filed for something described but not claimed in the parent? Yes, since the 2024 Rules. A divisional may be based on the disclosure in the parent’s provisional or complete specification whether or not it was claimed, and a divisional can itself be divided.
What is a patent of addition? A patent for an improvement or modification of an invention the same applicant has already applied for or patented. It cannot be challenged for obviousness over the main invention and pays no separate renewal fees, but it expires with the main patent.
Can a patent of addition outlive the main patent? Not ordinarily. If the main patent is revoked, the patent of addition can be converted into an independent patent for the rest of the original term, and renewal fees then become payable on it.
Is priority restoration available for a late convention filing in India? No. The twelve months is a hard limit. A later filing gets only its own Indian filing date.
Useful official resources
- IP India — patents — forms and fees for each route
See our related notes on provisional and complete specifications and entering the PCT national phase.
Deciding between a divisional and a fresh filing, or whether an improvement should be a patent of addition? Talk to us.