Applying for a green card based on entry to the United States on a K-1 fiancee visa is referred to as "adjustment of status." This process occurs after the wedding and is necessary for the new spouse to work or to travel outside of the United States. K-1 immigrants are eligible to receive a two-year conditional green card based on the marriage to their visa petitioner and only that petitioner.
Marry your U.S. citizen fiancee within 90 days of entering the United States on your K-1 visa. This must be the same fiancee who petitioned for the K-1 visa; you cannot adjust status based on marriage to another party.
Fill out the forms for your I-485 packet. Include the following forms: G-325A--Biographical Information for the immigrant spouse, I-693--Medical Examination of Aliens Seeking Adjustment of Status, I-485--Application to Register Permanent Residence or Adjust Status, I-765--Application for Employment Authorization (optional), I-131--Application for Travel Document (optional), G-1145--E-Notification of Application/Petition Acceptance (optional) and the I-864--Affidavit of Support.
Gather the remaining supporting information, including a copy of the immigrant spouse's complete passport and birth certificate, a copy of the Notice of Approval for the original I-129F petition, a copy of the immigrant spouse's I-94 form (front and back), a certified copy of your marriage certificate, two 2-by-2-inch passport-sized photos of the immigrant spouse and the current adjustment of status fee.
Make a copy of the entire packet, including the forms and the supporting information. Assemble the original forms and supporting information into a packet and mail to the USCIS lockbox address specified on the I-485 form. If you have applied for advanced parole and work authorization, you will receive these in about 90 days. You will also receive a notification of your biometrics appointment and your in-person interview.
Attend your biometrics appointment. The applicant will be fingerprinted and photographed and receive a receipt for attending the appointment.
Attend your in-person interview. Bring copies of the entire application packet and be prepared to answer questions about your relationship. If the interviewing officer is satisfied, your conditional green card will be issued.