Last week, the IRS released updated FAQs regarding reporting of employer provided health coverage on Form W-2. The updated FAQs incorporate guidance set forth in Notice 2012-9. Generally, employers filing more than 250 Forms W-2 must report the value of employer provided health coverage starting in calendar year 2012 (on Forms W-2 furnished to employees in 2013).
Find the FAQs here: http://www.irs.gov/newsroom/article/0,,id=237894,00.html
The FAQs include a link to a helpful chart that breaks down which types of coverage employers need to report on Form W-2.
Find the chart here: http://www.irs.gov/newsroom/article/0,,id=254321,00.html