There is one main difference between the U.S. Citizenship and Immigration Services (USCIS) Form N-400 and Form N-600. If you are not a U.S. citizen but want to become one, you file Form N-400. If you are already a U.S. citizen but need a certificate to prove it, you file Form N-600.

Form N-400, Application for Naturalization — If you are not a U.S. citizen but want to become one through naturalization, use Form N-400. It allows you to apply for U.S. citizenship. You can file Form N-400 once you meet all the citizenship requirements. It costs $680 USD to file Form N-400, including the $85 USD biometrics services fee for those required to pay it. (Biometrics services is when you get your fingerprints, photograph and signature taken.)

You might want to become a naturalized citizen if you are already a permanent legal resident of the U.S. but want more rights and benefits. Things a citizen can do that a permanent resident cannot include the following:

  • Vote
  • Serve on a jury
  • Travel with a U.S. passport
  • Bring family members to the United States
  • Obtain citizenship for your children under age 18
  • Apply for a federal job
  • Become an elected official
  • Eliminate risk of deportation
  • Receive federal grants and scholarships
  • Receive government benefits

Form N-600, Application for Certificate of Citizenship — If you are a U.S. citizen and need to prove it, use Form N-600. Form N-600 is not a request to become a U.S. citizen. It allows someone who became a U.S. citizen as a child through a parent’s citizenship to request a certificate that proves they’re a citizen. If you’re a U.S. parent requesting a certificate for a child you adopted, the filing fee for Form N-600 is $550 USD. For all other N-600 certificate requests, the fee is $600 USD. The filing fee can only be waived for U.S. military personnel or veterans applying for citizenship certificates for themselves.

You might need a citizenship certificate if, for example, you were born outside of the country. Your birth certificate reflects your birthplace, but you want a certificate that proves you are a U.S. citizen. In this example, you could ask the government for a citizenship certificate by filing Form N-600 according to the filing instructions.

N-400 and N-600 Overview

The main difference between Form N-400 and Form N-600:

  • Form N-400 helps you become a U.S. citizen.
  • Form N-600 helps you get a certificate that proves you became a U.S. citizen as a child through a parent’s citizenship.