Family-based immigrant visa applicants are issued visas pursuant to a quota system that mirrors the employment-based allocation system. Instead of being based on job requirements, however, family-based visa classifications are based upon the foreign national's relationship to the sponsoring U.S. citizen or permanent resident family member.
One major exception to the quota is “immediate relatives.” An immediate relative, according to INA § 201(b)(2)(A)(i), is a child, spouse or parent of a U.S. citizen except that, in the case of parents, the citizen must be at least 21 years of age. Note that a “child” is defined elsewhere in the Act as an unmarried person under the age of 21. It includes stepchildren of U.S. citizens who married the child's parent before the child reached the age of 18.
Because immediate relatives are exempt from numerical restrictions under the quota, there is never a backlog in visa availability for these close family members of U.S. citizens. This means that, if the foreign national is outside the U.S., the U.S. citizen petitioner must file an I-130 petition, wait for USCIS to approve it, and then the relative may immediately begin the process of applying for an immigrant visa at a U.S. consular post abroad. If the relative is in the U.S. and otherwise eligible for adjustment of status, then the I-130 petition may be filed concurrently with the Form I-485, Application for Adjustment of Status.