“The IRS is prevented from issuing liens or levies or other enforcement action,” Nina Olson, who holds a job called the National Taxpayer Advocate at the IRS, told a House hearing in August. “It can collect that mandate through what we call ‘refund offset,’ where a taxpayer has a refund coming to them and we would offset that refund amount with the amount of the penalty.”

The IRS will also determine who is eligible for taxpayer-financed subsidies to purchase health care on the exchanges that will be set up in every state. Anytime anyone’s situation changes — a raise, a new job, a move to another state — that person will be required to report it to the IRS for the purpose of recalculating their eligibility.

This is not a small group. Obamacare will give tax credits for the purchase of health coverage to people who make up to four times the poverty level — at the moment, that’s $44,100 a year for an individual and $88,200 for a family of four. Those millions of Americans had better keep the IRS informed of their status every step of the way.