During the US trademark application process, the United States Patent and Trademark Office (USPTO) may send you a trademark office action. A trademark office action is a communication from an examining attorney indicating why your trademark application cannot be approved. A non-final office action is typically issued after the examining attorney (1) reviews your trademark application, (2) reviews the Statement of Use, and/or (3) reviews an Amendment to Allege Use. In general, if your trademark application was filed directly with the USPTO, then you must respond to the trademark office action within three months of it being sent (or six months if you timely filed a Request for an Extension of Time to File a Response). On the other hand, if you’re seeking an extension of protection of your trademark in the United States through WIPO and the Madrid Protocol, then you must respond to the trademark office action within six months of it being sent.
If you don’t file a response by the deadline, your trademark application will go abandoned and you’ll be forced to begin the trademark registration process all over again (unless you’re eligible to file a Petition to Revive).