How to buy expired patents

A patent gives an inventor a limited time of exclusive ownership. If the patent expires, it's possible for someone else to buy it. Find out how to buy an expired patent.

by Brette Sember, J.D.
updated May 11, 2023 ·  2min read

A patent is a license that allows an inventor to be the only person or company allowed to make, use, or sell a specific invention. The patent is granted by the United States Patent and Trademark Office (USPTO) after the submission of an application and drawings. If that invention is not already patented, the inventor receives a patent after the materials are reviewed. Patents do not last forever, though, and they can lapse, providing the opportunity for someone else possibly to purchase the expired patent.

Cluttered desk with a desktop with the word "Patent" on the screen

Patent expiration

Utility patents expire four, eight, and 12 years after issuance of the patent if the maintenance fees are not paid at these points in time. The patent actually expires at 3.5 years, 7.5 years, and 11.5 years, but there is a six-month grace period in which to pay the maintenance fee. Once the fee is paid, the patent is renewed.

It is possible for the patent owner to reinstate the patent, if it expires, by paying a surcharge in addition to the maintenance fee. It's also possible for the patent holder to put the expired patent up for sale and sell the patent and their rights to someone else who could renew the expired patent by paying the fees. It is not possible for someone else to refile for an expired patent—that application would be denied, since there is an existing invention recognized by the USPTO.

If the maintenance fees are paid, a utility patent lasts for a total of 20 years. The patent expiration date for design and plant patents is 14 years after issuance.

Expired patents and public domain

After a patent has been in place for 20 years for utility patents and 14 years for design and plant patents, the invention becomes part of the public domain. This means the invention no longer has patent protection and is no longer off limits, so anyone can make, use, or sell the invention without infringement.

Where to find expired patents

If you are wondering how to find expired patents, follow these steps:

  1. Do a patent search through the USPTO.
  2. Select USPTO Patent Full-Text and Image Database (PatFT).
  3. Select Advanced Search.
  4. Input a date range or a specific date and begin the search.
  5. Choose the patent you want to research.
  6. Copy the patent number.
  7. Go to Public Patent Application Information Retrieval.
  8. Indicate that you are not a robot.
  9. Search using the patent number.
  10. Check to see if the patent is active, expired, or abandoned.
  11. If it is expired, you can proceed with trying to buy it.

How to buy an expired patent

Once you've located a patent that has expired, you can contact the patent owner and negotiate a sale. You can buy the invention and all rights to it, including the patent. You then renew the patent by paying the lapsed fees.

If the patent is past the 20- or 14-year mark (depending on the type of patent), you cannot renew the patent, but you can still own the product and any other materials and information you purchase from the inventor.

Managing and protecting your intellectual property—whether it is your own that you create, or someone else's intellectual property that you purchase—is important. You may want to work with an online services provider to help ensure that your intellectual property is adequately protected.

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Brette Sember, J.D.

About the Author

Brette Sember, J.D.

Brette Sember, J.D., practiced law in New York, including divorce, mediation, family law, adoption, probate and estates,… Read more

This portion of the site is for informational purposes only. The content is not legal advice. The statements and opinions are the expression of the author, not LegalZoom, and have not been evaluated by LegalZoom for accuracy, completeness, or changes in the law.