The K-1 fiancé(e) visa is for foreigners who wish to marry a U.S. citizen in the United States and then become legal permanent residents without having to leave the United States.  K-2 visas are for the children under 21 years old of K-1 applicants.

Fiancé(e) visas are different from other nonimmigrant visas, such as tourist or business visas. Whereas applicants for nonimmigrant visas must demonstrate strong ties to Brazil and the intention to return after a temporary visit to the United States, U.S. immigration law takes into account the fact that applicants for fiancé(e) visas intend to immigrate.

Note: Unmarried children under 21 years old may accompany the parent to the United States or may apply for a visa later, to join the parent after the parent has already entered the United States, been married, and become a permanent resident. If applying later, the child’s visa application must be made within one year of the date the parent’s fiancé(e) visa was issued.

Spouse of a U.S. Citizen (K-3) and minor children (K4):

The K3 visa is available to the spouses of United States citizens and their children under the age of 21 (K4) for whom an immigrant visa petition has been filed, but not yet approved by the Bureau of Citizenship and Immigration Services of the Department of Homeland Security (USCIS). The visa entitles the holder to travel to the United States to await the approval of the immigrant visa petition.