Immediate family can enter the US on a temporary visa while awaiting approval of Form I-130 (relative petition) or the availability of an immigrant visa. The spouse of a US citizen is eligible for a K-3 visa, while children of US citizens or K-3 visa holders are eligible for K-4 visas as long as they are under 21 and unmarried. To apply for a K visa with an I-130 already filed, the US citizen spouse files Form I-129F (petition for alien fiancee) with the US consulate in the country of marriage or, if that country is the US, in the alien spouse’s country of residence. The USCIS will continue the process by sending Form I-797 to the US citizen. A K-3 or K-4 non-immigrant receives his or her green card when both Form I-130 and Form I-485 (Application for Adjustment to Permanent Residence) have been approved. This process can take three to six months. If you enter on a non-immigrant visa and wish to work, you must file Form I-765 (Application for Employment Authorization) with USCIS, along with a $340 application fee.