Supplemental life insurance can be either pre-tax or post-tax, depending on how the premiums are paid. If the premiums are deducted from an employee's paycheck before taxes are calculated, then the coverage is considered pre-tax. On the other hand, if the premiums are paid with after-tax dollars, the coverage is considered post-tax. It's important to note that the tax treatment of supplemental life insurance can vary based on the specific plan and the employer's policies. Employees should consult their HR department or benefits administrator for detailed information about the tax implications of their supplemental life insurance coverage.