Let's say you're in the market for a new car. Prices are low, low, low. Every dealer is selling below invoice. You thought you could only afford a Chevy. You quickly realize that you can afford a Cadillac. What would you do?

If you're like most Americans, you buy the Cadillac.

For years, the nation's health care system has operated in much the same way. Because services aren't closely linked to responsibility for payment, we often buy more health care than we need.

Which is why we're intrigued by the idea percolating in the Senate Finance Committee to tax the richest health care plans.

Unlike salary or wages, workers pay no federal taxes on health care benefits provided by employers. This relic of the tax code dates to World War II, when wages were frozen by government fiat and employers began providing health care benefits in lieu of raises.

For years, tax-free health insurance has helped to create a perverse incentive in the system. Health care costs in the United States have risen 50 percent in the past decade while the economy expanded only 20 percent, and some studies suggest that as much as 30 percent of health care spending does little to improve patient care. We acknowledge that other important factors are at play — the fee-for-service model is a major problem. It rewards doctors, labs and hospitals for the number of procedures they perform instead of for keeping the patient well.

But don't underestimate the effects of a poor tax policy.

"Just like for anything else, if you got 30 percent off on your next car purchase, you'd probably buy a bigger car," Leonard Burman, director of the Tax Policy Center in Washington, D.C., told National Public Radio recently.

During last fall's campaign, we were cool to the idea of taxing benefits, but we now see that it would help to accomplish two important goals: containing costs and paying for extending coverage to the 46 million Americans who have none.

The Senate committee envisions levying a tax on insurance companies that offer what President Barack Obama has called "solid gold Cadillac" policies. This is only part of the solution and would be difficult politically. These plans aren't used only by the rich — many unions and government workers have them. And it's also true that this tax wouldn't raise enough money to cover the $1 trillion cost of reform over the next decade. A basket of other taxes and incentives would be needed. A surcharge on the wealthiest Americans is another good option.

But taxing health benefits, even in a limited manner, would inject some discipline into the market and send a powerful signal to industry players: The government is serious about "bending the cost curve" of health care in America.

Congress has three goals: covering every American, paying the bill for doing so and controlling health care costs. All three must be achieved for reform to succeed.

For that to happen, citizens must be persuaded that most of the time all they really need is a good, reliable Chevy — even if they want the Cadillac. Whether the average American is willing to make that choice will be clearer over the next few weeks.

REPRINTED FROM THE MILWAUKEE JOURNAL SENTINEL.