If ADP told you this, they are wrong. I have heard this before from other taxpayers, but ADP is still wrong.
Code W in box 12 is ONLY for HSA contributions.
Please direct your HR people to the W-2 instructions that make this very clear (page 22).
Code W—Employer contributions to a health savings account (HSA). Show any employer contributions (including amounts the employee elected to contribute using a section 125 (cafeteria) plan) to an HSA. See Health savings account (HSA).
The reference to a section 125 plan that the HSA contributions by the employee can be made by payroll deduction, like other section 125 plans. It does NOT mean that all section 125 plans can use code W.
I am sorry, but you need a corrected W-2.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
