On Monday, the application period opened for a new federal immigration program that allows undocumented spouses to remain in the United States while they apply for legal status. President Joe Biden announced the program, known as “parole in place,” in June through an executive action that could prevent the deportation of approximately 500,000 immigrants nationwide.

To be eligible, individuals must have lived in the United States for at least 10 years and must have been married to a U.S. citizen before the program was announced on June 17. Applicants can be disqualified if they have a criminal record or are considered a threat to national security.

“This is a huge game changer, probably the most significant immigration day in over a decade since DACA was announced,” said attorney Esther Valdés, referring to the Deferred Action for Childhood Arrivals program, which allows undocumented immigrants brought to the United States as children to remain in the country.

Before the “parole in place” program, federal law required many undocumented spouses of U.S. citizens to return to their country of origin and apply for a visa from a consulate abroad. Individuals approved under the new program will be allowed to remain in the United States as they navigate the path to citizenship.