The different requirements for each type of K visa are:
VISA (FIANCÉS OF U.S. CITIZENS):
The foreign national fiancé must be living outside of the U.S.;
The U.S. citizen must first file a Petition for Alien Fiancé with the United States Citizenship and Immigration Services (USCIS) and have it approved before the foreign national fiancé may apply for a K visa;
Both the U.S. citizen and the fiancé must remain unmarried until the arrival of the foreign national fiancé in the U.S.;
The foreign national fiancé and U.S. citizen must have met personally at least once in the two years before the K visa petition was filed.
VISA (SPOUSES OF U.S. CITIZENS):
The foreign national spouse must be living outside of the U.S.;
The U.S. citizen spouse must first file a Petition for Alien Fiancé with the United States Citizenship and Immigration Services (USCIS) and have it approved;
A Petition for Alien Relative for the benefit of the spouse must also have been filed, along with the Petition for Alien Fiancé;
If the marriage occurred outside the U.S., the U.S. consulate in the country where the marriage occurred must have issued the K visa.
AND K-4 VISAS (CHILDREN OF U.S. CITIZENS’ FIANCÉS & CHILDREN OF U.S. CITIZENS’ SPOUSES)
The children must be located outside of the U.S. and will accompany the K-1 or K-3 visa applicant or visa holder to the U.S.; and,
The children must be under twenty-one (21) years of age and unmarried.
LIMITATIONS ON K VISAS
The K Visa has various limitations associated with it. Some of these restrictions are as follows:
By law, non-immigrant aliens cannot change to K visa status while they are in the
U.S. The visa is only available to those living outside of the U.S.;
K-1 visa holders (foreign fiancés) must get married to their U.S. citizen fiancé within 90 days of their entry into the U.S.;
K visa holders may not change to any other non-immigrant status while they are present in the U.S.;
If a person is temporarily barred from entering the U.S. for a previous violation of U.S. immigration law, he or she may not use a K visa to enter into the U.S.;
The foreign national spouse may obtain work authorization from the United States Citizenship and Immigration Services (USCIS) during the visa waiting period.