Beginning May 5, U.S. Citizenship and Immigration Services (USCIS) will accept only the current edition of Form N-400, Application for Naturalization, dated 9/13/2013.
USCIS will reject and return all naturalization applications using previous versions of Form N-400 after Sunday, May 4, 2014. You can find the edition date at the bottom of any Form N-400 page.
USCIS issued the revised version of Form N-400 on February 4, 2014. As it transitioned to the redesigned Form, USCIS allowed applicants to continue using previous versions of Form N-400 for a 90-day transition period. This transition period ends on Sunday, May 4.