I came to the U.S. on a fiancée visa can I marry someone else?
A K1 fiancé visa is given to a foreign national for the purpose of entering the U.S. and marrying the U.S citizen who petitioned them. You have to get married within 90 days of entry to the person who filed for your visa. After you get married you apply for adjustment of status in order to obtain your green card in the United States. In the alternative you may leave the United States and file for your green card in your home country. (This is not generally done. The vast majority of people apply for their green cards in the United States. If you are thinking about doing this you need to realize that there will likely be a significant wait time in your home country for your green card. Please speak to an Immigration Attorney prior to leaving the United States)
If you decide to marry a different U.S. Citizen during the 90 day period you will not be able to obtain your green card through the new U.S. Citizen while you are in the United States on your fiancé visa. In this case it is extremely important that you consult with an experienced Immigration Attorney as soon as possible.
Most people think that marriage to a U.S. citizen will automatically take care of their immigration problems. That is not the case and someone who comes to the U.S.A. on a K1 fiancé visa and then doesn’t get married to the original petitioner of the Visa cannot request a change to another Visa status. If this is your situation you can apply for another visa but only after you leave the U.S. You do not want to be in the United States unlawfully, especially for 180 days as this would subject you to a 3 year bar from re-entering the United States. If you overstay your visa by more than one year then you could be barred from entering for 10 years.
Once you leave the U.S., you can always return on another visa or, if your situation warrants it, a green card.. This Visa could be a Fiancé visa filed by your current Fiancé or you could also apply for a marriage based immigrant visa if you marry a US Citizen or Lawful Permanent Resident. Be sure to speak to an experienced Immigration Attorney at the first sign of trouble with your fiancé visa. An experienced Immigration Attorney can guide you through the nuances of the K1 fiancé visa process.
Immigration laws can and do change. As this area of law can be tricky and you can suffer long-term consequences, you should always consult with an experienced Immigration Attorney about your specific situation.