The K-1 category permit a fiancée and the fiancée's minor children to travel to the United States for the purpose of marrying a US citizen fiancé. Men engaged to be married are fiancés and women engaged to be married are fiancées.  The K-1 category affords the foreign fiancé and his minor children K-1 and K-2 visas (respectively) valid for four months and requires the fiancé to marry his US citizen fiancée within 90 days of entering the United States.  To qualify the fiancés must have met in person within the two years preceding the petition, must be legally free to marry at the time the petition is filed (e.g. any existing marriage must have been terminated by a final order of dissolution before USCIS receives the K-1 petition), and the marriage must be legally possible according to the laws of the US state where the marriage will take place (e.g. no first cousins, etc.).  USCIS will sometimes waive the in person meeting requirement where the petitioner can demonstrate that it is contrary to his or his fiancée's culture or religion to meet in person before marriage, or that the US fiancé or foreign fiancée will suffer extreme hardship if they must meet in person.

The K-1 fiancé visa process requires the US citizen fiancé to file an I-129F petition with USCIS, wait for it to be approved and forwarded to the US consulate or embassy nearest to the foreign fiancée's residence, and then the foreign fiancée and her minor children, if any, must apply for K-1 and K-2 visas at the US embassy or consulate during an in person interview.  Although the K-1 and K-2 are nonimmigrant visas, they are like immigrant visas in many ways.  For example, they require a medical exam for every applicant that must be completed at a USCIS-approved physician in the visa applicant's home country.  And after entering the United States and marrying the US citizen fiancé, the K-1 and her K-2 minor children may apply to adjust status based on the approved I-129F petition and K-1/K-2 visas.  The foreign fiancée and her minor children do not require I-130 petitions and also normally do not require new medical examinations.

Those in K-1 and K-2 status may not extend their status.  Those who enter the United States in K-1 and K-2 status may work, but only after being granted employment authorization by USCIS under INA 274a.12(a)(6).  Most fiancés are admitted to the United States in K-1 status for a maximum of six months and USCIS takes about 90 days to issue an employment authorization card.

Interestingly, the fiancé visa laws treat the foreign fiancé's children more generously than the laws governing the spouses of US citizens.  For example, US law only permits a US citizen or permanent resident to petition for a spouse's children if the marriage occurred before the child's 18th birthday.  US immigration law defines a stepchild as a child who was under age 18 at the time of marriage.  A US citizen who married a foreign spouse with a child age 19 will face years of family separation because he is ineligible for a petition as a stepchild of a US citizen and the immediate relative category that his parent qualifies under does not allow derivative beneficiaries.  This odd result may be avoided by an odd strategy: for those who married after the foreign spouse's child reached age 18, the only possible solution is to divorce, for the foreign spouse to renounce US residence, and then for the US ex-spouse to file a fiancée visa petition with USCIS. 

Courts are divided on whether the K-2 children of K-1 finacées should be subject to the same restrictions on adjusting status based on some other category if the K-1 parent is no longer married.  Section 245(d) of the Immigration and Nationality Act clearly only allows K-1 and K-2 adjustment when the K-1 adjusts based on the same marriage described in the K-1 visa.  For some countries' nationals, this may be a tricky, but worthwhile strategy that can save more than twenty years of family separation.  For example, Mexico's visa backlog for a permanent resident's petition for a minor child is 1.5 years.  In our situation above, the foreign spouse would need to file a petition for her son and hope that it is approved before he reaches age 21 (the Child Status Protection Act will allow her to deduct from the son's age any period of time the petition is pending with USCIS - this may or may not provide sufficient help depending on how long USCIS takes to process the mother's I-130 petition).  If the child is over 21 at the time the priority date becomes current (after subtracting from his age any time the I-130 petition was pending as allowed by CSPA), he will now fall into the F2B category for unmarried sons and daughters of permanent residence.  Once that happens, he is subject to an inevitable 20 year wait to immigrate to the United States because of the backlogs for unmarried sons and daughters born in Mexico of US permanent residents.  What about if the mother applies for US citizenship after being married to the US citizen fiancé for three years?  This does not help because the visa backlog for Mexican unmarried sons and daughters of US citizens is the same - about twenty years.  A family in this situation will have difficult choices to make and not a lot of time to decide what to do.

Generally, those who enter the United States in K-1 status are not permitted to adjust status based on an I-130 petition filed by any other US citizen or permanent resident spouse - even if the petition is filed years later and based on a marriage entered into years later.

Courts are divided on whether the K-2 children of K-1 finacées should be subject to the same restrictions on adjusting status based on some other category if the K-1 parent is no longer married.  Section 245(d) of the Immigration and Nationality Act clearly only allows K-1 and K-2 adjustment when the K-1 adjusts based on the same marriage described in the K-1 visa.

One circuit court has held that a K-2 is able to adjust status after "aging out."  Carpio v. Holder, 592 F.3d 1091 (10th Cir. 2010).

The Board of Immigration Appeals also held that while an alien admitted in K-1 status may not adjust status based on a marriage to another person, he may adjust status based on the marriage to the US citizen petitioner even if the marriage ended.  The Board held that where a foreign national enters the United States in K-1 status, marries the US citizen K-1 petitioner within 90 days and is later divorced, the K-1 beneficiary may apply to adjust status under INA 245(d) even though the marriage to the US citizen petitioner is no longer valid and without the US citizen ex-spouse's cooperation.  Matter of Sesay, 25 I&N Dec. 431 (BIA 2011).

In another important decision, the Board of Immigration Appeals held that a K-2 child of a nonimmigrant fiancée visa holder is not barred from adjustment of status under INA 245(d) even though he was 21 years old or older at the time he applied to adjust status.  Matter of Le, 25 I&N Dec. 541 (BIA 2011).