USPTO Begins New Trademark Serial Number Series

The United States Patent and Trademark Office introduced a new series of eight-digit trademark application serial numbers starting July 18, 2026. Numbers now begin with 50 for applications filed under sections 1 or 44 of the Trademark Act.

The change maintains the eight-digit format and does not affect priority determinations, which continue to rely on filing dates and times. Special series such as the 79 series for Madrid Protocol filings remain unchanged.

The update supports internal processing efficiency as application volumes grow. Existing applications retain their original serial numbers.

Trademark attorneys advise clients that the new prefix has no substantive impact on examination or rights but serves administrative purposes.

Sources: https://www.facebook.com/uspto.gov/posts/a-change-is-coming-to-trademark-application-serial-numbersstarting-july-18-2026-/1432205592278578/ https://blog.trademarkelite.com/2026/08/default