Who can apply ?
A K1 visa allows a U.S. citizen to petition to bring a fiance in the United States in order to marry. It is only a preliminary step to obtaining permanent residence. Both members of the couple must be single and of legal age to marry. The petitioner must be a U.S. citizen, the couple must intend to marry and generally have met and seen each other in person within the past two years.
The first step is that the U.S. citizen must file a petition at the INS regional service center nearest the home of the U.S.-citizen fiancée. The Step Two application is carried out by the foreign national at the U.S. consulate in their country of residence.

Family members:
The unmarried, minor children of a K1 beneficiary derive "K-2" nonimmigrant visa status from the parent so long as the children are named in the petition. A separate petition is not required if the children accompany or follow the alien fiance(e) within one year from the date of issuance of the K1 visa. Thereafter, a separate immigrant visa petition is required.

Documents required:
Petition: 1. Form I129F
2. Form G-325A (one form for each party)
3. One identification photograph each of the petitioner and beneficiary.
4. Documents proving that both parties are legally free to marry.
5. Documents showing that the foreign national has real intent to marry the petitioner and why the petitioner cannot travel to the beneficiary's home country and marry .
6. Documents proving that the couple has physically met within the past two years.
7. If the couple has not met and their religion does not allow meeting before marriage: a letter from an authority in the religious organization verifying that both parties are members of that religion and explaining why they cannot meet.
8. If the couple has not personally met but to do so would cause extreme hardship: letter explaining the extreme hardship preventing the petitioner from traveling to meet the beneficiary.

Application:
1. OF forms
2. Form F-864
3. Form I-765
4. Notice showing approval of the fiancée visa petition.
5. All documents originally filed with the petition.
6. Long-form birth certificate for the applicant and each accompanying child.
7. Passports for the applicant and each accompanying child, valid for at least six months beyond the date of the final interview.
8. Police certificates form every country in which the applicant and each accompanying child has lived for at least six months since the age of 16.
9. Three photographs each of the applicant and each accompanying child.
10. Form I-864, Affidavit of Support, for the applicant and each accompanying child.