Personally, I wouldn't have went through all the legal wranglings Robert did to try and determine constitutionality. I would have taken Congress at its word. In other words, they said the mandate was a penalty and treated it as such. However, I see Roberts’ point that previous SCOTUS rulings have defined certain elements that are required for something to be, in fact, a penalty, and that criteria doesn't fit the mandate.
Can Congress encourage certain behaviors by giving income tax breaks? Apparently it can. It certainly does. Could it do the opposite, assign a higher tax rate to someone for not doing something it wants? I'm trying to think of an instance like that, but I'm drawing a blank. Nevertheless, there's a very small distinction in my opinion between giving out tax breaks based on behavior and assigning tax increases for same.
That blasted 16th Amendment was written so poorly it pretty much allows the federal government to do whatever it wants with our incomes. I think we need some constitutional amendments to reign in the madness.
In this case "behavior" is being born. No one is excluded from these laws. Tax credits are meant to alter behavior, but they don't apply to everyone unless they choose to engage in that behavior. I don't have to buy an energy saving furnace.