Most medical carriers have made the decision to extend adult dependent coverage to age 26 effective June 1, 2010 ahead of the proposed healthcare reform legislation. This is to cover the large number of dependents who would otherwise drop off as they graduate and are no longer full time students. The carriers anticipate an increase in premium of 1% for this extension of coverage. For most carriers this increase will take place with the plans renewal.
Based on regulations issued today however, the employer cannot pass this additional surcharge on to the employee.
For more information, see the article below by Jerry Geisel of BusinessInsurance.com.