Patent Priority Date

Condition: Non-provisional filed within 12 months of provisional; claims supported by provisional disclosure

Most common startup strategy. File a provisional to stake a date, then file the non-provisional within 12 months. Claims not supported by the provisional get the non-provisional filing date as their priority date.

Condition: No prior application; claims are supported by the original specification

Direct filing. Priority date equals filing date. Any public disclosure of the invention before this date (by the inventor or anyone else) is prior art under AIA § 102(a)(1), subject to the 1-year grace period exception for the inventor's own disclosures.

Condition: Filed while parent is pending; properly claims benefit under § 120

Continuation: all claims supported by parent spec get parent's priority date. CIP: claims to new matter added in the CIP get the CIP's own filing date — those claims see all of the parent's prosecution as prior art.

Condition: PCT filed within 12 months of priority application; national phase entered by 30-month deadline

PCT preserves international filing rights from the earliest priority date. If a US provisional is filed first, followed by PCT within 12 months, the PCT (and all national phase entries) claims the provisional's priority date.

Condition: US application filed within 12 months of foreign filing; foreign application is from a Paris Convention or TRIPS member country

35 U.S.C. § 119(a): an applicant who filed in a foreign country first can claim that foreign filing date as priority in the US, provided the US application is filed within 12 months. Common for companies that file in their home country first.

Disclosure type

Grace period?

Details

Inventor's own disclosure

Yes — 1 year

Under AIA § 102(b)(1)(A): an inventor's own disclosure made 1 year or less before the effective filing date is NOT prior art. This gives US inventors a 1-year grace period after their own public disclosure to file.

Third-party disclosure after inventor's own disclosure

Yes — if inventor disclosed first

Under AIA § 102(b)(1)(B): a third-party disclosure that is 'by another' but made AFTER the inventor's own public disclosure is also not prior art. The inventor's prior public disclosure shields subsequent third-party disclosures of the same subject matter.

Independent third-party disclosure before filing

No

If a third party independently discloses the same invention before the inventor's effective filing date (and before any inventor disclosure), that is prior art under § 102(a)(1). No grace period applies to independent third-party disclosures that predate the inventor's filing.

Third-party patent or published application

No grace period for pre-filing art

A third party's patent or published application that is effective before the inventor's effective filing date is prior art under § 102(a)(2). No grace period. This is why filing date is critical in competitive fields — a competitor's published application with an earlier effective date is devastating prior art.

What is a patent priority date?

A patent's priority date is the earliest date from which the patent's claims are effective against prior art — it determines what disclosures and patents can be used as prior art to challenge the patent's validity. Specifically, the priority date is the earliest filing date in the patent's priority chain from which the claims are supported. Under the America Invents Act (AIA, effective March 16, 2013), the United States uses a first-inventor-to-file system (not first-to-invent). The applicant who files first (with a properly supported claim) wins a patent dispute between two applicants claiming the same invention — not the applicant who invented first. This makes filing date critical: (1) An earlier effective filing date means fewer potential prior art references can be used against the claims; (2) An earlier filing date means you filed before a competitor who may be working on the same technology; (3) For non-AIA applications (pre-March 16, 2013 patents under 'first-to-invent' rules), priority is more complex — but for any modern application, file first. The priority date is set by the earliest application in the priority chain that: (a) contains sufficient disclosure (written description) to support the claims as filed; and (b) was properly claimed as priority in all subsequent applications in the chain. An application cannot claim priority back to a parent if that parent does not disclose the claimed subject matter — those claims get the filing date of the application in which the new disclosure appears.

How does a provisional patent application affect the priority date?

A US provisional patent application (35 U.S.C. § 111(b)) establishes a priority date at the cost of $320 (large entity), $160 (small entity), or $80 (micro entity) plus attorney fees, without requiring the formal requirements of a non-provisional application (no claims required, no oath). The provisional's priority benefit: (1) Any non-provisional application filed within 12 months of the provisional can claim the provisional's filing date as its priority date — but only for claims that are fully supported by the provisional's disclosure; (2) The 12-month priority window gives the applicant time to test the market, seek investors, or improve the invention before committing to full patent prosecution; (3) The 12-month period is strict — there is no extension; missing the 12-month deadline forfeits the provisional's priority date; (4) The provisional establishes priority only if the claims in the non-provisional are supported by the provisional's written description — if the non-provisional claims subject matter not disclosed in the provisional, those new claims get the non-provisional's filing date, not the provisional's. Critical disclosure requirement: the provisional must describe the invention with enough detail that a person of ordinary skill in the art could make and use the claimed invention (enablement). A provisional that is too thin or vague may not support the claims in the non-provisional, leaving the applicant with the non-provisional's filing date. Strategy: the provisional should disclose as fully as practicable — treat it like a real specification, not a placeholder. A strong provisional gives maximum protection and maximum flexibility for claims in the non-provisional.

What is the AIA's first-inventor-to-file system and how does it affect me?

The America Invents Act (AIA), signed in 2011 and fully effective for applications with any claim having an effective filing date on or after March 16, 2013, changed the US patent system from 'first-to-invent' to 'first-inventor-to-file.' Under the pre-AIA first-to-invent system: if two inventors filed for the same invention, the USPTO held an interference proceeding to determine who actually invented first — based on evidence of conception and reduction to practice. An inventor who could prove earlier conception and diligence in reducing to practice could overcome a competitor who filed first. Under the AIA first-inventor-to-file system: the patent goes to the first inventor who files a patent application with sufficient disclosure, regardless of who invented first. Being second to file generally means losing, even if you invented first. There is no interference proceeding — only derivation proceedings (if a later filer is accused of having derived the invention from the earlier inventor). The 1-year grace period still exists: an inventor's own disclosures (publications, public use, offers for sale) in the year before filing are NOT prior art under § 102(b)(1)(A). But a third party's independent disclosure of the same invention before your filing date IS prior art with no grace period (for third-party disclosures not preceded by your own disclosure). Practical implications: (1) File as early as possible — a low-cost provisional establishes your priority date immediately; (2) Don't delay filing after a public disclosure (conference paper, product launch, investor pitch) — the 1-year clock is running; (3) In competitive technology fields, monitor published patent applications from competitors — an application with an earlier priority date for overlapping claims is a serious problem.

How does the 1-year grace period work under the AIA?

Under 35 U.S.C. § 102(b)(1), certain disclosures made within 1 year before the patent application's effective filing date are excluded from prior art — this is the 1-year grace period. Who benefits from the grace period: (1) The inventor's own disclosures: if the inventor publicly discloses the invention (publishes a paper, presents at a conference, demos at a trade show, offers for sale) within 1 year before the effective filing date, that disclosure is NOT prior art against the inventor's own application. (2) Third-party disclosures that follow the inventor's prior public disclosure: if the inventor disclosed first, and then a third party disclosed the same subject matter, the third-party's disclosure is also not prior art (as long as the third party's disclosure came after the inventor's). Who does NOT benefit: (1) An independent third party who discloses the same invention before the inventor's filing date (and before any inventor disclosure) — that disclosure IS prior art with no grace period; (2) A third party's US patent or published application with an earlier effective filing date — also prior art with no grace period under § 102(a)(2). The grace period is narrower than many inventors believe: the US grace period is NOT reciprocal with most countries. In Europe, Japan, China, and most other patent systems, any public disclosure before the filing date is absolute prior art — no grace period at all. This means that an inventor who publicly discloses and then relies on the US 1-year grace period to file within 12 months has LOST their right to file in virtually every other country. Foreign patent rights are destroyed by pre-filing disclosure with no grace period. Startup strategy: file a provisional application BEFORE any public disclosure (investor pitches, conference presentations, product launches, publications). This preserves both US and international rights.

How do I claim priority from a foreign patent application?

Under 35 U.S.C. § 119(a) and the Paris Convention, a US patent application can claim priority to a foreign patent application filed in any Paris Convention or TRIPS member country (which includes virtually all major economies). Priority claiming requirements: (1) The US application must be filed within 12 months of the foreign application's filing date (6 months for design patents under § 172); (2) The foreign application must have been filed in a Paris Convention or TRIPS member country; (3) The US application must include a claim for priority to the foreign application, identifying the country, filing date, and application number; (4) A certified copy of the foreign application must be provided to the USPTO (can be waived if the foreign application is available in a digital library the USPTO can access, e.g., EPO, JPO). What Paris Convention priority gives you: the US application is treated as if it were filed on the foreign application's filing date for novelty and prior art purposes. This is valuable when you file in your home country first and want US rights — the 12-month window lets you use your foreign filing date as your US priority date. PCT path: if you file a PCT application within 12 months of the foreign application, the PCT claims the foreign priority date. National phase entries from the PCT inherit that priority date. This is the most common international filing strategy: file in one country (or file a provisional in the US) → file PCT within 12 months (claiming the first filing's priority date) → enter national phase by month 30 in target countries.