“Do I have to file adjustment of status within 90 days of my arrival in the United States?”
The short answer is no. When you come into the United States on a K-1 Fiance Visa you must marry within 90 days. That the important timeframe to remember but you can file for adjustment of status any time after that. Now, keep in mind you cannot work or travel until you’ve received your green card or your travel permit and your employment authorization document. So we’ve seen a lot of cases where someone came into the United States on a fiance visa, they got married but they didn’t file for adjustment of status and then they had to go back home for a family emergency and then they couldn’t get back into the country. They had to then file for a spousal visa. So again, you don’t have to file for adjustment of status within 90 days. You must simply get married within 90 days. It is recommended that you file for adjustment of status obviously for all of the benefits but also so you can travel and work.
It is important to note that if you exit the country while in unlawful status, you may receive a temporary ban on your way out. It is highly recommended to adjust your status before attempting to leave the country.