If you meet certain requirements, you may become a US citizen either at birth or after birth. Use this form to apply for US citizenship.This form is available to file online. Welcome to the Suffolk County Clerk's Office. At one time or another either directly or indirectly, every resident of Suffolk County deals with our office. CARECEN operates the Office of New Americans' Nassau and Suffolk Opportunity Centers to provide naturalization application assistance free of charge. Our Citizenship Module will help you in completing the application, assembling all necessary supporting documents, and submitting the correct filing fees. You have to first obtain a Marriage License and then have a Marriage Ceremony in the City Clerk's Office or a Marriage Ceremony outside the City Clerk's Office. A foreign national spouse of a US Citizen is almost always entitled to come to the United States and become a lawful permanent resident (green card holder). Find out which types of historic naturalization records are available through the court archives and how to access them.