The One-Year Rule: File Within One Year of Public Use or Sale — Or Lose Your Rights
This is the single most common way inventors lose their patent rights, and it catches people off guard every day. Under US patent law, if you publicly use, sell, offer for sale, or publicly disclose your invention, you have exactly one year to file a patent application. Miss that deadline and your invention becomes unpatentable — permanently.
There is no extension. There is no appeal. There is no way to fix it after the fact.
The safest approach is always to file before any public use, sale, or disclosure. The one-year grace period exists as a safety net, not a strategy. Treating it as a countdown clock is risky because the triggering event is not always obvious, and once the deadline passes, the damage is irreversible.
What Triggers the One-Year Clock
Under 35 USC 102, several types of events start the one-year countdown:
Public Use
Any use of the invention that is accessible to the public — even if only one person sees it — can start the clock. This includes:
- Demonstrations at trade shows, conferences, or industry events
- Field testing in a non-confidential setting
- Using the invention in your business where customers or the public can observe it
- Letting others use it without a confidentiality agreement
Public use does not require that anyone actually understood or paid attention to the invention. If the use was accessible to the public, it counts.
Commercial Sale or Offer for Sale
Selling the invention or offering it for sale triggers the one-year period, even if:
- The sale was to a single customer
- The product was not yet manufactured — an offer to sell is enough
- The sale was informal or verbal
- The product was sold under a different name or brand
- Only a prototype was sold
The on-sale bar applies when there is a commercial offer for sale of a product embodying the invention, and the invention is ready for patenting (either reduced to practice or described in enough detail to enable the patent). The Supreme Court confirmed this two-part test in Pfaff v. Wells Electronics (1998).
Published Descriptions
Publishing a description of the invention starts the clock. This includes:
- Marketing materials — brochures, catalogs, website pages describing how the product works
- Academic papers or conference presentations
- Press releases or news articles
- Social media posts describing the invention in enough detail to enable it
- YouTube videos or other online demonstrations
- Patent applications published by the USPTO (your own or others’)
What Does NOT Trigger the Clock
- Confidential disclosures under a signed non-disclosure agreement (NDA)
- Internal company use that is not accessible to the public
- Private testing in a controlled, non-public environment
- Discussions with your patent attorney (protected by attorney-client privilege)
The Critical Difference: US vs. International
The one-year grace period is a feature of US law only. Most other countries — including Europe, China, Japan, and the countries covered by the Patent Cooperation Treaty (PCT) — operate under an absolute novelty standard. This means any public disclosure, use, or sale before the filing date destroys patent rights in those countries. There is no grace period.
This is why filing before any public activity is so important. If you rely on the US one-year grace period, you may preserve your US patent rights but lose the ability to file in every other country in the world. For inventors who may want international protection, this can be a devastating and irreversible mistake.
For more on international filing strategy, see our guide to International Patent Protection.
Real-World Scenarios
Scenario 1: Trade Show Demonstration
You demonstrate your new agricultural tool at a farm equipment show in March 2026. The demonstration is open to the public. Your one-year deadline to file a US patent application is March 2027. Your international filing rights were lost the moment you demonstrated the tool (unless you had already filed a provisional or other application before the show).
Best practice: File a provisional patent application before the trade show. Cost is minimal compared to losing your patent rights.
Scenario 2: First Commercial Sale
You sell your first unit of a new oilfield tool to a customer in June 2026. Your one-year deadline is June 2027. It does not matter that you only sold one unit, or that the customer did not know the product contained a patentable invention.
Best practice: File before the first sale. If the product is ready to sell, it is ready to file.
Scenario 3: Website Product Listing
You add a new product to your website with a “buy now” button and a description of how the product works in September 2026. This is both a public disclosure and an offer for sale. Your one-year deadline is September 2027.
Best practice: File before the product page goes live.
Scenario 4: Investor Pitch Without an NDA
You pitch your invention to a group of investors at a networking event in January 2026 without having anyone sign an NDA. If your pitch described the invention in enough detail to enable it, this may qualify as a public disclosure. Your one-year deadline may be January 2027.
Best practice: Either have investors sign NDAs before the pitch, or file a provisional application before pitching.
Scenario 5: The Ambiguous Trigger
You start using a new manufacturing process in your factory in April 2026. The factory is not open to the public, but delivery drivers, vendors, and contract workers pass through regularly. Is this “public use”?
This is exactly the kind of gray area that creates risk. If any non-employee could have observed the invention in use, a court might find that the one-year clock started. When the trigger is ambiguous, the safe move is to file sooner rather than later.
How to Protect Yourself
File Before Any Public Activity
This cannot be overstated. The safest and simplest approach is to file a patent application before any public use, sale, offer for sale, or disclosure. A provisional patent application costs a fraction of a full filing and preserves your rights — both in the US and internationally. It buys you 12 months to prepare a full non-provisional application while maintaining your priority date.
Use NDAs for Pre-Filing Disclosures
If you must discuss your invention with others before filing — potential partners, manufacturers, investors — use a written non-disclosure agreement. An NDA makes the disclosure confidential rather than public, which means it does not trigger the one-year clock. Make sure the NDA is signed before any substantive discussion of the invention.
Document Everything
Keep records of:
- When you first conceived the invention — dated notes, sketches, emails
- Every instance of use, demonstration, or disclosure — who saw it, when, where, and under what circumstances
- Every sale or offer for sale — dates, customers, terms
- All NDAs — signed copies with dates
This documentation helps your patent attorney assess your filing deadline and provides evidence if the timing is ever challenged.
When in Doubt, File Now
If you are unsure whether a triggering event has occurred, or when exactly it happened, the prudent course is to file immediately. A provisional application can be prepared quickly and affordably. The cost of filing a provisional is negligible compared to the cost of losing your patent rights entirely.
The Consequences of Missing the Deadline
If you miss the one-year deadline:
- Your invention is unpatentable in the US. No exceptions, no extensions.
- You cannot fix this. There is no petition, appeal, or workaround.
- Your own public activity becomes prior art against you. The USPTO will reject your application based on your own disclosure or sale.
- Competitors can freely copy your invention. Without patent protection, there is no legal mechanism to stop them (unless trade secret protection applies, which is unlikely if the invention was publicly used or sold).
This is not a theoretical risk. It happens to inventors regularly, and it is almost always preventable.
Frequently Asked Questions
Does the one-year rule apply to provisional patent applications? Filing a provisional application does not start the one-year clock for a non-provisional filing — it establishes a priority date. However, if you have already triggered the one-year clock through public use or sale, your provisional must be filed within that year. The provisional itself must then be followed by a non-provisional within 12 months of the provisional filing date.
What if I sold the product but the buyer did not know the invention was inside it? The on-sale bar applies regardless of whether the buyer understood the patentable aspects. If the product embodying the invention was sold or offered for sale, the clock starts.
Does an NDA always protect me? An NDA protects you only if it is signed before the disclosure and covers the subject matter discussed. Verbal agreements to keep things confidential are harder to enforce and riskier to rely on. Use a written NDA.
What if I am not sure when the triggering event occurred? Consult a patent attorney immediately. The attorney can help you identify potential triggering events and assess your remaining time. If there is any ambiguity, filing a provisional application as soon as possible is the safest course.
Does the one-year rule apply to design patents? Yes. The same statutory bars under 35 USC 102 apply to both utility and design patent applications.
Disclaimer: All fees and cost estimates on this page are for informational purposes only and do not constitute a binding quote. Actual costs vary based on the complexity of the invention, USPTO fee schedules, exchange rates, and other factors. Contact Shannon Warren for a specific estimate tailored to your situation.
Concerned about your filing deadline? Do not wait. Contact Shannon Warren immediately to discuss your situation. If you have publicly used, sold, or disclosed your invention, time may be running out. A provisional patent application can be filed quickly to preserve your rights while you evaluate your full filing strategy.