If you are a U.S. citizen or lawful permanent resident, then as soon as you and your immigrant spouse are married, you can file the Petition for Alien Relative (Form I-130) with U.S. Citizenship and Immigration Services (USCIS).
This is the first step for any alien who wishes to immigrate to the United States as the relative (spouse or otherwise) of a U.S. citizen or a lawful permanent resident (green card holder). The form is not filed by the prospective immigrant, but rather signed and submitted by the petitioning U.S.-based family member.
Form I-130's main purpose is to prove to the immigration authorities that:
Because the I-130 petition is only the start of the process, its approval by USCIS does not give the intending immigrant any right to enter the United States, nor any guarantee that a green card will ultimately be approved.
For some immigrants, namely spouses of U.S. citizens, the process will likely be relatively quick. If living overseas, you will be able to proceed with your green card application immediately after USCIS approves the I-130, by applying for an immigrant visa through a U.S. consulate in your home country.
If you are already living lawfully in the U.S. or here after a lawful, non-fraudulent entry (even if you overstayed), you won't have to wait for I-130 approval to file your adjustment of status (AOS) application, but can file the I-130 and their AOS application concurrently.
For other spouses, however, the process will be more complicated.
For instance, spouses of U.S. citizens who entered the U.S. without inspection (illegally) are not eligible to adjust status in the United States; though they might still be eligible for a green card through another method, called consular processing. They will have to await approval of the I-130 petition, then travel to their home country for a visa interview.
Unfortunately, they may be barred from return to the U.S. for a number of years based on their history of unlawful presence in the United States, having become "inadmissible." After a one-year unlawful U.S. stay, the inadmissibility bar is ten years outside the country; unless they successfully apply for a waiver.
Fortunately, what's known as the "provisional waiver" allows many such spouses to submit their waiver application before leaving the U.S., to avoid the risks of being barred from return if the waiver is denied.
For intending immigrants married to lawful permanent residents, the process will also require multiple steps. They are in the second "preference" category of visas, and therefore face annual limits on the number of visas available in their category. Because the demand for visas is always greater than the supply, they might wait several years between approval of their I-130 and being allowed to go forward with their application for lawful permanent residence. It's often a wait of up to around five years.
Due to the complexities of this process, you might be interested in hiring an attorney; see How Much Does a Lawyer Cost for a Family or Fiancé Visa Application?
Here are some important things to know about preparing and submitting USCIS Form I-130:
For the most current filing address and fee, see the I-130 page of the USCIS website or call the USCIS Contact Center at 1-800-375-5283.
If you're filing an I-130 for an immediate relative spouse (that is, you are a U.S. citizen), then just as soon as that petition is approved, your relative can apply for an immigrant visa and green card.
If the relative lives overseas, this needs to be done through a U.S. consulate or embassy. If the person lives in the United States after a legal entry, then he or she may be able to "adjust status" through USCIS. But check with an immigration attorney to be sure.
If your relative is eligible to adjust status as an immediate relative, then you don't actually have to wait until I-130 approval to submit the full green card application; you can do it all at once.
Once the I-130 petition is filed and approved, relatives in preference categories (spouses or unmarried children under 21 of a U.S. permanent resident) must wait for an immigrant visa number. How long they wait depends entirely on how many other people in their category had an I-130 approved on their behalf ahead of them, and on which country the alien is from. Because of per-country limits, people from certain parts of the world wait extra long; usually those from Mexico, China, India, and the Philippines.
Progress on the waiting list is measured by the immigrant's Priority Date, which comes from the date that USCIS received the I-130 petition. To find out the current Priority Dates for immigrant visa numbers based on country and category check the latest Visa Bulletin.
Once an immigrant number is available, the eligible relative can apply for an immigrant visa, most likely through an overseas U.S. consulate. In a few rare cases, such as immigrants who've been living legally in the United States, the immigrants may instead be allowed to apply for adjustment of status, a process which is done without leaving the United States. Talk to an immigration attorney before trying this.