It's changes to the 2013 W2 for the 2012 calendar year.
The following lists what has to be included on the W2.
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2012 W-2 Reporting Requirements: What Is Included?
Major medical
Medicare supplemental*
Medicare Advantage*
""Mini-med"" plan
On-site medical clinics
Employer contributions (including flex credits
employee elects to apply) to health FSA
Employer contributions to hospital or fixed indemnity plan, or specified disease or illness insuranceWellness benefits
(if program qualifies as a health benefit)
Employee assistance plan (except referral only)
Executive medical coverage (insured or self-funded); includes executive physical and screenings and supplemental coverage)