How should I identify a national stage application when communicating with the USPTO?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

When communicating with the USPTO regarding a national stage application, it’s important to use the correct identification information. The MPEP provides specific guidance:

“Once an international application entering the U.S. national phase (“national stage application”) has been accorded a U.S. application number (the two digit series code followed by a six digit serial number), that number should be used whenever papers or other communications are directed to the USPTO regarding the national stage application.“

To ensure proper processing and expedited handling, include the following information:

• The eight-digit U.S. application number (primary identifier)
• The international application number
• The international filing date
• The national stage entry date under 35 U.S.C. 371 (if accorded)

Using this information helps cross-check and prevent errors in application identification.