Green Card Test (continued)
Green cards are approximately the size of driver's licenses. They are no longer green in color, but still hold the name. Most green card holders have valid social security numbers and must follow the same tax laws as U.S. citizens, including the requirement to report worldwide income on their tax returns. Treat a taxpayer who possesses a green card as a resident alien for tax purposes.
See Publication 4588, Basic Tax Guide for Green Card Holders.