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    Grace periods are a rescue, not a plan

    Only some countries forgive your own disclosure, each counts the time differently, and none stops a third party who files first.

    Lesson 3 of 8 · 6 min

    A line drawing of an hourglass rising from a block of black obsidian

    A grace period is a window in which your own earlier disclosure does not count against your later patent application. Only some countries forgive your own disclosure, each counts differently, and none stops a third party from filing first (WIPO table).

    The US rule

    The US excepts an inventor's own disclosures made one year or less before the effective filing date, which is generally the date of the earliest application that properly supports your claims (35 U.S.C. § 102).

    Six systems compared

    Check these against the date shown under Current.

    • United States. 1 year. Covers your own disclosure. Runs back from the effective filing date. No step at the outset, then a Rule 1.130 declaration or specification statement when needed (35 U.S.C. § 102).
    • Europe (EPC). 6 months. Covers only evident abuse or a recognized exhibition, not your own general disclosure (EPC Art. 55). For an exhibition, state it at filing and supply a certificate within 4 months (EPC Rule 25). The period runs from the actual European filing date, so an earlier priority filing does not stretch it, according to a secondary reproduction of the case law (xepc.eu).
    • China. 6 months. Covers four listed events only. Runs back from the priority date, if any. Declare at filing and give proof within 2 months (CNIPA Guidelines).
    • Japan. 1 year. Covers your own disclosure. Runs back from the filing date. For your own act, state it at filing and prove it within 30 days (Japan Patent Act).
    • Korea. 12 months. Covers your own disclosure. Runs back from the Korean filing date, with a domestic-priority exception, and a treaty priority claim does not rescue the deadline. For your own act, state it at filing and prove it within 30 days, or use a later route (MOIP Guidelines).
    • Canada. 1 year. Covers your own disclosure. Runs back from the Canadian filing date (for an international PCT application, the international filing date), not the priority date (Patent Act s. 28.2). WIPO's entry lists no declaration step (WIPO table).

    A worked example

    This example is our judgment, drawn from the sources above. You disclose on day 0, file a US provisional application at month 11 and file abroad at month 23. The US may be fine (35 U.S.C. § 102). Canada and Korea are late (Patent Act s. 28.2; MOIP Guidelines). Your European rights were lost on day 0 (EPC Art. 55).

    Timeless wisdom

    WIPO's rule is the universal one: "avoid any disclosure of an invention that might affect its patentability until the patent application has been filed" (Inventing the Future). Even the generous US grace period has limits. If you disclose first, its shield against third parties who disclose after you covers only the same subject matter, and obvious variations stay prior art (MPEP § 2153.02). If the year ends on a weekend or federal holiday, it rolls to the next business day. Adding a statement about an earlier disclosure after filing may also be new matter, meaning content the application did not originally contain (MPEP § 2153.01).

    What's current

    As of November 6, 2026

    The US shield narrowed. Sanho v. Kaijet (July 31, 2024) held a private but non-confidential sale did not "publicly disclose" subject matter (opinion). NCS Multistage v. Nine Energy (September 14, 2026, precedential) held the patentee's own earlier sale was not a "public disclosure" under § 102(b)(1)(B), so a third party's later sale stayed prior art (opinion). Your own sale can still fall inside the separate (A) exception (MPEP § 2152.04).

    Canada's consultation closed June 23, 2026 with no rule change proposed (CIPO). Our China details come from the 2023 Guidelines, under which the meeting exception excludes provincial-level meetings (CNIPA Guidelines). Grace-period changes in the 2026 edition were not reported but are not ruled out (CNIPA). WIPO's table shows status as of August 2024 (WIPO table). Whether a foreign priority claim affects Japan's year is unconfirmed.

    Key takeaways

    • File before you disclose, because a grace period is a rescue, not a plan.
    • Countries differ on length, on what is covered and on the date the period runs back from.
    • Europe and China do not cover an inventor's general disclosure.
    • The US shield against third parties covers only the same subject matter.

    Check your understanding

    1. You publish your invention on day 0, file a US provisional at month 11 and file abroad at month 23. In the lesson's example, what happens in Europe?
    2. You publish first. A third party then publishes an obvious variation of your idea before you file in the US. What does the US shield do?

    Sources

    1. WIPO grace period table (status August 2024)
    2. 35 U.S.C. § 102
    3. MPEP § 2153
    4. EPC Art. 55
    5. EPC Rule 25
    6. xepc.eu reproduction of G 3/98 and G 2/99
    7. CNIPA Patent Examination Guidelines (2023 edition)
    8. Japan Patent Act
    9. MOIP Patent Examination Guidelines (February 2026)
    10. Canada Patent Act s. 28.2
    11. WIPO, Inventing the Future
    12. Sanho v. Kaijet (Fed. Cir. 2024)
    13. NCS Multistage v. Nine Energy (Fed. Cir. 2026)
    14. MPEP § 2152
    15. CIPO consultation on the patent grace period
    16. CNIPA notice on the 2026 Guidelines

    The Academy is general education, not legal advice, and reading it doesn't create an attorney-client relationship. Patent law and fees change, so check the linked sources and have a registered patent attorney or agent review your situation before you file. Obsidyan sells patent software, including AI drafting tools, so weigh what these lessons say about AI tools with that in mind.

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