Under ACA, any payments or reimbursements to employees for Non-ACA Approved Group Health Plan, must be treated at taxable compensation, subject to Social Security and Medicare Tax. This includes payments made to/through Section 125 Plans (Flexible Spending Accounts) meaning, only group insurance through the SHOP Marketplace qualifies for pre-tax treatment.
Please contact your payroll service immediately to ensure that you are in compliance with this aspect of ACA. If done before first quarter payroll tax returns are prepared, it will be easier to make any necessary adjustments to Employer/Employee Payroll Taxes.
This provision has not been extended like certain other Affordable Care Act mandates.