Registration begins for one of the biggest immigration policy changes in decades when an estimated 500,000 spouses of U.S. citizens become eligible to apply for legal status without having to leave the country first.

Under the policy that Joe Biden announced in June, many spouses without legal status will be able to apply for something called “parole in place,” offering permission to stay in the U.S., apply for a green card and eventually get on a path to citizenship.

Previously many feared that if they left the country, they might not be allowed re-entry.

To be eligible, they must have been continuously in the U.S. for at least 10 years, not pose a security threat or have a disqualifying criminal history and have been married to a citizen by June 17 — the day before the program was announced.

They must pay a $580 fee to apply and fill out a lengthy application, including an explanation of why they deserve humanitarian parole and a long list of supporting documents proving how long they have been in the country.

Al Jazeera.