On August 6, 2002, Congress passed the Child Status Protection Act (“CSPA”) to provide “age-out protection” to child beneficiaries. The CSPA allows certain children who are derivative beneficiaries of an immigrant visa petition to be classified as a “child” under immigration law even if the child has already reached age 21 by the time he can apply to adjust status. In April 2008, USCIS issued a memo that provides guidance on how the CSPA applies in both family-based and employment-based immigration cases. See 2008 USCIS memo for your reference.
USCIS will use the following formula for employment-based derivative beneficiaries: The child must be under 21 (as defined by USCIS, i.e. “CSPA age”) on the date a visa becomes available (priority date). The CSPA age is calculated as follows:
The age of the child when the priority date becomes current.
Subtract any time that a filed immigrant petition was pending adjudication (i.e. I-140) (this can take anywhere from 6 months to a year).
In other words, even if the child is, on paper, over 21 at the time a visa is available, he or she can still be considered locked in “under 21” and thus eligible depending on how long the I-140 visa petition was pending because this timeframe can be subtracted from his age.
Upon calculation, if the CSPA age is below 21, the child must seek to acquire a green card within one year of when the priority date became current.
On a following note, we now know there are two visa bulletins issued by Department of State of when one can file an I-485, even if it is before to the priority date. As the regulations and guidance are currently, USCIS will likely calculate the CSPA age based on the priority date (Final Action Dates, first chart) rather than the second chart (Chart B). However, we are still monitoring to see if they will issue any further guidance considering these two bulletins. Thus as a conservative route, go by the Final Action Dates chart when determining age-out issues.
In the alternative, for some scenarios where you know the child will be surely “aging out” by the time a visa is available, there are other avenues such as switching the person to F-1 status to continue their time in the U.S. But that is something to be further explored by the beneficiaries themselves, as we cannot say for sure when the visa numbers will change again (and they do).