Quick answer
File a provisional that fully describes everything you are about to show. Then publish, present or pitch only what it covers. If you will show more, file an updated provisional first. File the PCT or foreign applications within 12 months of the first provisional. You do not usually need to wait for the PCT before you publish.
This is the same rule as file first, then talk, with one condition added: the provisional has to be as complete as what you disclose.
Why a provisional is usually enough
A US provisional gives you a priority date. Within 12 months you can file abroad and claim that date. Under the Paris Convention (Article 4B), acts in those 12 months, including your own publication, cannot invalidate the later filing. At the European Patent Office, the priority date counts as the filing date for novelty (EPC Article 89). In the US, the provisional date counts for claims it supports (35 U.S.C. 119(e)).
So a talk or book that shows only what the provisional fully describes is not prior art against those claims, in the US or in the countries that respect priority.
Where it goes wrong
- The provisional is thin. At the EPO, a claim gets the earlier date only if a skilled reader can derive it "directly and unambiguously" from the provisional as a whole (Enlarged Board opinion G 2/98). Slides, an abstract or one drawing often fall short.
- You disclose more than the provisional covers. Anything you publish in the 12 months counts as prior art in Europe against claims that do not get the priority date (G 3/93). That includes your own book.
- You disclosed before the first filing. Europe treats that as prior art. The US and Japan each have a grace period, but they work differently (see below).
- You miss the 12 months. After that there is no priority to claim.
- The company does not own the invention yet. Get the inventor-to-company assignment signed before the PCT, so the right party claims priority.
Grace periods compared
| United States | Europe (EPO) | Japan | |
|---|---|---|---|
| Your own disclosure before filing | Excused if within one year before the effective filing date (35 U.S.C. 102(b)(1)(A)) | No general grace period | Excused if within one year before the Japanese or PCT filing date (Patent Act Art. 30) |
| Counted from | The effective filing date, which can be the provisional date | — | The actual Japanese or international filing date, not the US provisional date |
| What you must do | Show the disclosure was yours if an examiner cites it | — | Claim it at filing (for a PCT, in the request or at Japanese entry) and file proof of each disclosure |
| Leaks against your will | Covered as an inventor-originated disclosure | Only "evident abuse", within six months before the actual European filing (EPC Art. 55) | Covered if you file within one year; no proof is needed at filing |
A dated example
This example is made up. A founder files a US provisional on 15 January 2027 that fully describes the core method.
| Date | Event | Covered by the provisional? |
|---|---|---|
| 1 Dec 2026 | Blog post showing the core method | Same content, but posted before filing |
| 15 Jan 2027 | US provisional filed | — |
| 10 Mar 2027 | Conference talk on the core method | Yes |
| 1 Jun 2027 | Book published, with a new chapter on variant X | No |
| 14 Jan 2028 | PCT filed, claiming the provisional and adding variant X | — |
| Disclosure | US | Europe | Japan |
|---|---|---|---|
| Conference talk | Safe | Safe | Safe |
| Variant X in the book | Safe: within one year before the PCT | Lost: the book is prior art against variant X | Can be saved: within one year before the PCT, if the grace period is claimed and proved |
| Blog post | Safe: within one year before the provisional | Lost: it came before the priority date | Lost: 13½ months before the PCT filing date |
The talk is the rule working: it came after a full provisional and stayed inside it.
The book could have been safe everywhere. A second provisional on variant X, filed before 1 June 2027 and claimed in the PCT, would have protected it without relying on any grace period.
The blog post is the trap. It looks harmless in the US because the provisional came six weeks later. But Japan counts its year back from the PCT date, so the post falls outside it, and Europe never had a grace period to offer.
Pitches and conferences
- Investors: talk about the market, the team, traction and what the product does. Hold back how it works until a filing covers it. A pitch to people bound to secrecy is generally not a public disclosure, but many investors will not sign NDAs. Japan's guidelines list "briefing sessions for investors or customers" as a way an invention gets published when attendees have no duty of secrecy.
- Conferences: treat a talk as publication. Slides, recordings and abstracts are public. NDAs are not practical here.
- Selling or offering the product: a separate risk in the US. Sales and offers can count as prior art even when they are confidential. Raising money is usually not an offer to sell the invention, but check before a pilot or pre-order.
Keep a disclosure log
Keep one line per disclosure: date, venue or URL, who presented, exactly what was shown, and a copy (slides, the book's copyright page, a screenshot). Before each new disclosure, and again before the PCT, compare the log with your provisionals.
Japan's Patent Office asks for these same facts in its proof of disclosure: date, place, who published, contents, and objective evidence such as a conference program or the book's copyright page. If you ever need Japan's grace period, the log is most of the work.
Common questions
Do I need to wait for the PCT application before publishing?
Usually not. A provisional that fully describes what you will publish generally protects that material in the US and abroad, if the PCT or foreign applications follow within 12 months. Waiting for the PCT matters when you expect to publish more than the provisional covers.
Does the US one-year grace period protect me in Europe?
No. Europe has no general grace period. A book, talk or website showing the invention before your filing or priority date counts against you there. The exceptions cover only evident abuse and officially recognized international exhibitions.
Does Japan have a grace period?
Yes, one year under Patent Act Article 30, but it counts back from the Japanese or international (PCT) filing date, not the US provisional date. You have to claim it and file proof of each disclosure.
Is pitching investors under an NDA a disclosure?
A pitch to people bound to secrecy is generally not a public disclosure. Many investors will not sign NDAs, so the more reliable control is to keep technical detail out of the pitch until it is covered by a filing.
What if my book covers more than my provisional?
File an updated provisional covering the new material before the book comes out, and claim priority from both provisionals in the PCT. Otherwise the new material can be lost in Europe, and in Japan it depends on claiming the grace period.
Sources: Paris Convention Art. 4B · EPC Arts. 54, 55, 87–89 · EPO Enlarged Board G 2/98, G 3/93, G 1/15 · 35 U.S.C. 102(a)(1), 102(b)(1), 119(e) · MPEP 2152–2153 · Japan Patent Act Arts. 30 and 184-14 · JPO, Operational Guidelines for Applicants to Seek the Application of Exceptions to Lack of Novelty of Invention (2018 revision, updated December 2020). Checked 2026-11-06. Other countries, including China and Korea, have their own rules and are not covered here.
Planning a book, a talk or a raise before you file? That timing question is what Andrew's startup patent strategy advisory is built around.
Warning & Disclaimer
Human Authored · AI Assisted · Just being transparent
Andrew Leung is a registered patent agent and an entrepreneur. This article reflects general educational information and professional judgment about early founder patent decisions. Nothing on this website constitutes legal advice nor creates an agent-client relationship. Patent laws vary by jurisdiction and change over time. For foreign filings, work with a qualified practitioner in each country. For legal advice specific to your situation, consult a registered patent attorney.
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