Work as a principal actor in a Screen Actors Guild member film. If you are cast in a principal or speaking role in a union film with a SAG member producer, you will be eligible for a SAG card. This can be tricky, since most union film producers can't hire an actor that doesn't already have a SAG card.
Provide proof of employment as a background actor with a production company signed to a SAG agreement. You must have worked as a background actor a minimum of three days for a producer who has a contract with SAG, and who promises to cover background actors at full SAG wages and conditions. Copies of pay stubs or vouchers from the production company will not be accepted. You must provide a report from the payroll department that contains your name and social security number; the production company name, the exact title of the production you performed in; the dates you worked and the amount you were paid.
Join a SAG-affiliated union for a minimum of one year. An actor will be eligible for SAG membership after being a full-paid member for at least a year of one of the following affiliate unions: the American Guild of Variety Artists (AGVA), the Alliance of Canadian Cinema, Television and Radio Artists (ACTRA), the American Federation of Television and Radio Artists (AFTRA), the Actors Equity Association (AEA), or the American Guild of Musical Artists (AGMA).
Fill out a SAG application with proof of eligibility documentation and submit it to SAG, where it will be evaluated. Make an appointment in advance with your local SAG office if you wish to submit your application in person, or mail it along with your full name, date of birth, address, and phone number to the mailing address provided on the SAG website.