Once U.S. Citizenship and Immigration Services (USCIS) approves Form I-129F, Petition for Alien Fiancé, its valid for a period of four months. This period of validity is different than the term of the K-1 visa which is only valid for a period of 90 days.
Form I-129F Validity
After USCIS approves Form I-129F, the engaged couple to make arrangements for the foreign national fiancé to come to the United States for marriage. Since these arrangements involve a wedding and, in most cases, a permanent move to the U.S., planning can be time-consuming. During this four-month period, the couple should try to secure plane tickets and the necessary travel documents for the foreign fiancé to enter the United States.
Expired Form I-129F
If you and your fiancé are unable to make the necessary arrangements within the four-month period, you may be able to request an extension. A consular officer can extend the validity of the petition if it expires before visa processing is completed.
Once the K-1 fiancé enters the United States, he or she has no more than 90 days to marry and file an adjustment of status application (Form I-485). If the foreign national does not marry or decides not to apply for a green card through adjustment of status, he or she must depart the U.S. before the K-1 expires.