What are the rules regarding contributions made by an employer?

If an employer makes contributions to its employees' HSAs and does not allow employees to make pre-tax payroll contributions, the employer must make available comparable contributions on behalf of all employees with comparable coverage during the same period. Contributions are considered comparable if they are either of the same amount or the same percentage of the deductible under the plan. If employer contributions do not satisfy the comparability rule during a period, then the employer is subject to an excise tax equal to 35 percent of the aggregate amount contributed by the employer to HSAs for that period.