While the Obaucus bill is pretty bad, it would appear that Senator Baucus is intent on making it worse.

Now, according to opencongress.org, the tax penalty for not buying insurance will only be enforced against those who overpay their taxes. The penalty will be taken from tax refunds. So, if you want to get out of paying the tax, there is a simple way: don’t overpay your taxes.
In fact, underpay your taxes.
The government can’t take a dime from you if you don’t give them any extra. This is one more example of how the Obaucus bill would cause problems for the health insurance market. People will now spend more time trying to get out of paying the tax, than either paying the tax or getting health insurance. This also significantly waters down the incentive to get your own health insurance.