There is a misconception that someone who marries a U.S. citizen automatically acquires U.S. citizenship by marriage. This is simply not true.
Marriage to a U.S. citizen can certainly expedite someone's path to citizenship, but the alien still needs to wait several months to actually receive a green card, and then several years after that to become eligible to apply for citizenship.
So how does someone become a U.S. citizen after marrying a U.S. citizen? Here are four general steps:
Be eligible for citizenship. To be eligible for citizenship through marriage, someone needs to be a permanent resident, be at least 18 years old, and have lived in the United States for at least three years. During those three years, the person must have been married to the U.S. citizen, been physically present in the country for at least half of that time, and not have established a home outside the country.
Apply for naturalization. Assuming you meet the eligibility requirements, you still must apply for naturalization to become a citizen. Generally, you must complete Form N-400, Application for Naturalization, include photographs with your application, get fingerprinted, and submit other documents. You may also be asked to provide documents proving the validity of your marriage.
Interview and take the citizenship test. Typically, after your application and fingerprints are processed, the next step is to interview with an immigration official and take the citizenship test. At the interview, you will be asked questions about your application, marriage, and background. If the interview goes well, you will then take an English and civics test. Oftentimes, your interview may stand in place of the English test, as the interviewer will have a sense of your command of the English language. The civics test can be more difficult and will require some studying.
Swear allegiance. The final step to becoming a U.S. citizen is taking an Oath of Allegiance to the United States.
Keep in mind that this is a very high-level summary of the naturalization process for someone married to a U.S. citizen. Many things can go wrong during naturalization, and you will want to talk to an immigration attorney should you have any questions.