What taxes are not with held under section 125?

Under IRS Section 125 eligible expenses such as medical premiums can avoid income tax (both federal and state), these monies through the use of a Section 125 plan also avoid FICA (Social Security and Medicare) taxes on both the employee and employer matching contribution. Federal Unemployment Tax is exempt and in most cases State Unemployment Tax however depending on the state in can be classified as either a tax or insurance so you will need to determine the state for eligibility. For a list of states that have specific requirement see related link.