When doing nothing is illegal

My last post got me thinking about how to rejigger things to encourage more donations to private charities.

Maybe we should mandate donations to private charities. Instead of raising taxes on the rich, require that they give X% of their income to the 501(c)3 charities of their choice.

I think that would definitely be better than sending the money through the Washington DC (or Beacon Hill) tax-money-sausage-factory... but would it be constitutional?

Libertarians and conservatives are arguing that the Individual Mandate in Obamacare is unconstitutional. That you can't claim that doing nothing (not buying health insurance) is illegal.

There is at least one thing you're legally required to do in the United States, even if you do absolutely nothing besides being an 18-year-old male. I was legally required to register for the draft; the Supreme Court decided that the constitutional power to "raise and support armies" makes that OK.

I can't think of any other laws that apply if you do absolutely nothing-- are there any? You have to pay income tax, but only if you earn income (which is doing something-- and besides, imposing a national income tax required a constitutional amendment). Requiring that rich people donate to charity is logically just another form of income tax... but legally? I dunno.

To keep the lawyers happy we'd probably have to jack up the tax rates on the rich and then give a tax credit for charitable donations. Which would make the whole scheme complicated enough you'd get the right complaining about high tax rates and the left complaining about rich people using tax deductions to get out of paying their fair share.