What Is a Patent Family? Provisionals, Continuations, and Foreign Filings

A patent family is a group of patent applications and patents connected to the same original filing, usually through priority claims. A family might start with one provisional application and grow to include a U.S. non-provisional application, several continuations, an international application, and patents in other countries, all describing the same invention and relying on the same early filing date. Understanding how families work helps you plan filings, read a competitor’s portfolio, and answer investors’ questions accurately.

The starting point: priority

Every family traces back to a first filing that establishes a priority date. Later applications that claim the benefit of that filing can rely on its date for subject matter it describes. That date matters because prior art is measured against it: something published after the priority date generally cannot be used against claims entitled to that date.

The key word is “entitled.” A later application receives the earlier date only for what the earlier application actually disclosed. New material added later gets the later filing date. Entitlement is decided claim by claim, so applications in the same family, and even claims in the same patent, can have different effective filing dates.

Members of a U.S. family

Provisional application. An optional first filing that holds a date for 12 months. It is not examined on its own and never becomes a patent, but a non-provisional application filed within 12 months can claim its benefit (35 U.S.C. 119(e)).

Non-provisional application. The application that is examined and can issue as a patent. It may claim the benefit of a provisional, or it may be the family’s first filing.

Continuation. A new application with the same specification as a pending earlier application (the parent), pursuing different claims (35 U.S.C. 120). Continuations are used to pursue broader claims, claims directed at a specific product, or claims the parent’s examination did not reach. They generally must be filed while the parent, or a qualifying intermediate application in the same chain, is still pending.

Divisional. A later application, filed while the parent is pending, that pursues an invention the examiner required the applicant to set aside in a restriction requirement. A divisional pursues claims to the non-elected invention, and 35 U.S.C. 121 provides certain protection against double patenting rejections based on the parent when the divisional stays consistent with the restriction.

Continuation-in-part (CIP). An application that repeats a substantial portion of a parent’s specification and adds new material. Claims supported by the parent can rely on the parent’s date; claims that depend on the new material get the CIP’s own filing date.

Patents issuing from continuations and divisionals generally share the term of the family. Term usually runs 20 years from the earliest non-provisional filing date relied on under 35 U.S.C. 120 or 121, so adding family members does not extend the overall period of protection. Provisional applications do not count toward that 20-year term.

International members

Foreign applications. Applications filed in other countries can claim priority to the first filing if they are filed within 12 months, under the Paris Convention.

PCT application. An international application under the Patent Cooperation Treaty, also generally filed within 12 months of the first filing. It does not become a patent itself. It preserves the right to pursue protection in the many member countries and defers that decision, typically until about 30 months from the priority date, although national phase deadlines vary by jurisdiction, and some allow 31 months or more.

National and regional phase applications. The applications filed in individual countries or regional offices, such as the European Patent Office, when the PCT application enters those jurisdictions. Each is examined under local law and can issue as a local patent.

These foreign applications and patents are often called counterparts of the U.S. family members.

An example family

A typical family for a startup might grow like this:

• Month 0: U.S. provisional application filed before a product launch.
• Month 12: U.S. non-provisional application and PCT application filed, both claiming priority to the provisional.
• Month 30: PCT application enters the national phase in Europe and Japan.
• Year 3: The U.S. non-provisional is allowed. While that application is still pending, before the issue fee is paid, the company files a continuation to pursue claims directed at a competitor’s new product.
• Year 4: A CIP is filed to cover a significant improvement, with the new material receiving the CIP’s filing date.

At that point, one provisional has grown into a family with U.S. patents, pending U.S. applications, and foreign applications, all connected by priority.

Why families matter

Coverage over time. Keeping one family member pending lets the company pursue new claims as products and competitors change, within the limits of the original disclosure.

Valuation and diligence. Investors and acquirers usually evaluate patents by family, since family members share a disclosure and often a term. Counting patents without understanding the families can overstate or understate a portfolio.

Reading a competitor’s portfolio. A competitor’s single issued patent may be one member of a larger family with pending applications that could still produce new claims. Checking for related pending applications is part of understanding any patent you are concerned about.

Related obligations. Family members can be linked in ways that matter later, such as terminal disclaimers that require commonly owned patents to remain under common ownership in order to stay enforceable.

A practical takeaway

When you file a first application, think of it as the start of a family rather than a single filing. Plan the decisions that come at 12 months, at international phase entry, and at each allowance, and keep a simple record of which applications belong to which family and what each one claims. Your patent attorney or agent can help you map an existing family and identify where it can still grow.