If you are a U.S. permanent or conditional resident—that is, someone with a green card—the basic rule is that you cannot apply for U.S. citizenship (or apply to naturalize) until you have lived in the United States as a lawful permanent resident for at least five years. That means exactly five years, to the day. For example, if you were approved for permanent residence on April 17, 2015, you would be eligible for citizenship on April 17, 2020. Check your green card (permanent resident card) for the exact date on which you became a permanent resident.

If you start out as a conditional rather than a permanent resident (most likely because you got your residence either through recent marriage to a U.S. citizen or through an investor visa), your two years as a conditional resident count as permanent residence, on one condition: You must successfully become a permanent resident at the end of those two years. (You may be able to apply before that USCIS approval comes through, however, as described in Conditional Resident Awaiting I-751 Approval? Consider Filing N-400 for Naturalization.

Any one of several exceptions may, however, reduce the amount of time you must wait.

Keep reading for a rundown on these exceptions—or at least the ones that apply to civilians. If you are a member of, or relative of someone who has been with the U.S. Armed Forces, see U.S. Citizenship Application Rules for Military Members and Veterans.

90-Days Early Application Rule

Despite the five years of permanent residence requirement, you are actually allowed to submit your naturalization application to U.S. Citizenship and Immigration Services (USCIS) within the 90-days before your five-year anniversary has arrived. The reason has to do with timing.

Your application must be submitted by mail, using a form provided by USCIS called an "N-400." USCIS will take a long time to process the N-400, to arrange for you to be fingerprinted, and to call you in for the interview at which it actually reviews your application, tests you on your knowledge of English and U.S. government, and makes a decision on whether to approve or deny you.

In fact, USCIS will in all likelihood take at least 90 days to call you in for your interview, which is why it has officially said that you are safe applying within that time period.

Exception to Five-Year Rule for People Married to a U.S. Citizen

You need to wait a mere three years to apply for U.S. citizenship if, during that time, you have been a permanent (or conditional) resident married to, as well as living with, a U.S. citizen. (See the Immigration and Nationality Act at I.N.A. Section 319(a) or 8 U.S.C. Section 1430(a).) You will need to provide proof that you qualify along with your application.

This exception applies even if you did not get your green card through this marriage. So, for example, you could have gotten a green card through your employer, then married a U.S. citizen soon after, and you still need wait only three years from the date of your marriage to apply for citizenship.

You will, however, need to stay married to your U.S. citizen spouse all the way past your citizenship interview and approval, and through your swearing in as a U.S. citizen (at the oath ceremony). The exception won't work if you separate or divorce legally prior to being sworn in as a citizen, or even if you choose to stop living with your spouse.

Unfortunately, you will also lose the exception if your spouse dies before your naturalization interview.

Exception to Five-Year Rule for Battered Spouses of a U.S. Citizen Granted VAWA Protection

Congress didn't want immigrants to have to stay in an abusive marriage for three years just to obtain the benefit of the three-year exception when they applied for U.S. citizenship. So it created an exception for people who got their green cards through marriage to a U.S. citizen, but based on a self-petition on Form I-360 due to the fact that the U.S. citizen is physically or emotionally abusive. These immigrants can apply for U.S. citizenship using the three-year exception.

Children can also use this exception, although they must still reach age 18 before submitting their application for citizenship.

Partial Exception to Five-Year Rule for Refugees

If you got your green card based on having come to the United States as a refugee, part of your time as a refugee can be counted as if you were a permanent resident (known as "rollback").

If you were granted refugee status while you were in another country, use the date you entered the United States as the beginning of your permanent residence. No matter how many years you lived in the United States as a refugee before eventually becoming a permanent resident, those years will count as if you had been a permanent resident the whole time. (See the U.S. Code of Federal Regulations, at 8 C.F.R. Section 209.1(e).)

Partial Exception to Five-Year Rule for People Granted Asylum (Asylees)

If you got your green card based on having received asylum in the United States, one year of your time as an asylee counts as if you were a permanent resident (known as "rollback").

Note, however, that if you waited longer than one year after receiving asylum to apply for your green card, that extra time will not be counted toward your permanent residency period. You will have to wait a full four years from the actual date when you're approved for a green card.

And, somewhat confusingly, you will need to wait a full five years from the date your green card says you became a permanent resident. That's because USCIS will automatically backdate your permanent residence approval date on your green card by one year, in recognition of your rollback rights. (See the U.S. Code of Federal Regulations 8 C.F.R. section 209.2(f).)

Exception to Five-Year Rules for Spouses of U.S. Citizens in Certain Overseas Jobs

If your spouse has a job requiring the two of you to live overseas, you may be able to apply for citizenship without five years of permanent residence. If you are willing to come back to the United States to apply, you can file your application any time after you receive your permanent residence.

There are a number of limitations on who can use this provision. You must be regularly stationed abroad due to your spouse's employment. You also must declare an intention to live in the United States when your spouse's employment ends. And finally, your spouse's employer must be either:

• the U.S. government (such as the C.I.A., the military, the Peace Corps, or the American Red Cross)
• a U.S. research institution that has been recognized by the U.S. attorney general (these are listed at 8 C.F.R. Section 316.20(a))
• a U.S. firm or corporation (or a subsidiary) that is engaged wholly or partly in developing U.S. foreign trade and commerce
• a public international organization in which the United States participates by treaty or statute (these are listed at 8 C.F.R. Section 316.20(b) and (c)), or
• a religious denomination that has an organization within the United States; your spouse must perform ministerial or priestly functions there or work solely as a missionary.

Other Requirements for Citizenship May Require You to Wait Even Longer

A final note of caution: Even if you have spent the required amount of time with a green card, you may need to wait longer before applying for U.S. citizenship if you either:

• have not spent the required amount of time physically present in the United States (for most people, at least half of your required years as a permanent resident)
• have not lived in the district or state where you are filing your application for at least three months
• have spent more than a year outside the United States, or
• cannot yet demonstrate that you've had good moral character for the required amount of time before applying for citizenship.

See the resources listed below for more details on these related requirements.

More Information

For details on all the rules and exceptions described above, including tips on how to prove you qualify for one of the exceptions, see the book Becoming a U.S. Citizen: A Guide to the Law, Exam, & Interview, by Ilona Bray (Nolo). And if you would like a personal analysis of your situation, consult an experienced immigration attorney.