McCain, on the other hand, would use the tax code to shift insurance from the workplace to the marketplace. Under his plan, employees would start having to pay income tax on the value of the healthcare premiums they receive from their employers, making it a less attractive benefit. At the same time, McCain offers a tax credit of $2,500 for individuals and $5,000 for families toward the cost of coverage at work or in the private, nongroup market.
The upshot, analysts say, is that many young, healthy workers would reject their employers' taxable insurance benefit and either go without or find a high-deductible, low-premium policy on the private market. This would leave employers with an insured base of older, less healthy workers, which would drive up the cost of their insurance. The likely result is that many companies would drop coverage altogether.
...
After a Republican primary campaign in which candidates and debate moderators rarely mentioned healthcare, healthcare specialists are beginning to take notice of the radical base of McCain's plan. David Snow, the CEO of Medco, the largest US manager of drug benefits, told the National Press Club this month that McCain's plan "will create chaos."
Robert Laszewski, a Washington-based consultant on benefits, has said that under the McCain plan most companies would stop paying for healthcare in three to four years....
Another danger with the McCain plan is that these nongroup insurers would compete by cherry-picking the healthiest individuals to cover and charging steep premiums to those with preexisting conditions or family histories of diseases. McCain's answer to this is that he would work with the states to expand the existing system of "high-risk pools" for the hard to insure. But these plans charge such high premiums with such limited benefits that in 2006 fewer than 200,000 people had enrolled in them.
http://www.boston.com/bostonglobe/editorial_opinion/editorials/articles/2008/09/21/worlds_apart_on_healthcare/