Obama's Health Tax

What is a tax? Wouldn't the requirement to buy insurance (regardless of anything you do, such as driving) constitute a tax? Certainly the dictionary would say so:
"a charge…imposed by authority on persons or property for public purposes” is commonly considered a tax."

Anyway, it appears now that there may be a 2.5% of income penalty if someone does not purchase health insurance and a 11% of income "tax" (or compulsory premium) to buy health insurance. It will be interesting to see how many opt for the penalty instead of the tax.

http://reason.com/archives/2009/11/04/obamas-hidden-fees

http://republicans.waysandmeans.house.gov/webreturn/?url=http://cbo.gov/ftpdocs/106xx/doc10691/hr3962SubsidiesRangelLtr.pdf