I have come across a situation where two employees are paying their own health insurance through payroll deduction and a third employee is actually getting 100% reimbursed for his premiums on a personal plan. Is any of the reimbursed premiums taxable

I have come across a situation where two employees are paying their own health insurance through payroll deduction and a third employee is actually getting 100% reimbursed for his premiums on a personal plan. Is any of the reimbursed premiums taxable? There is no written policy.