The employees of the city of Greenville must make mandatory contributions to the city's postretirement health benefit plan. The employees' contributions are placed in a trust and are used exclusively for the employees' benefits. The employees believe that because they are required to make the contributions from their base salaries, the result should be the same as if the employer made the contribution and had reduced their salaries by the amount of the contributions. Therefore, the employees believe they should be permitted to exclude the payments from gross income. The employees have asked you to research the issue.