There are a number of different ways for a legal citizen of the United States to be able to bring her or his foreign fiancée into the country, but each kind of fiancée visa comes with different types of requirements. It is important to make sure that you have a full understanding of the required documents as well as the criteria for eligibility before making any kind of application for an immigrant visa meant for your fiancée.
A K1 and K2 visa, otherwise sometimes referred to simply as a dual intent visa, is issued to someone who is engaged to be married to a citizen of the United States. If this visa is granted, then the person to whom it has been granted is required to marry their United States citizen partner within no more than 90 days of entering the country. Their status will then be adjusted to that of a permanent citizen.
Should the foreign-born citizen have children, they can then apply for a K2 visa that allows unmarried children to be able to enter the United States. In order to put in an application for a K1 visa, a petition must first be filed with the United States consulate on behalf of the fiancée.
The spouse of a US citizen is allowed by the K3 and K4 visas to waive approval from the US Citizenship and Immigration Services via the U-130 petition and is allowed to enter the US. The K-4 visa can also be applied to unmarried children who are below the age of 21.