Can someone apply for a citizenship after three years from the date of marriage or after three years of getting green card?

You have been a permanent resident for 3 years or more and meet all eligibility requirements to file as a spouse of a U.S. citizen. See the "Spouses of U.S. Citizens" link under "Citizenship by Naturalization" to the left.

You have been a permanent resident for at least 5 years and meet all other eligibility requirements. See the "General Path to Naturalization" link under "Citizenship by Naturalization" to the left.