Washington ? Do Americans spend so much on health care because they are not taxed on the insurance benefits they get at work?

Increasingly, the conventional wisdom in the health care debate says yes: Any Econ 101 student knows that because employer benefits are excluded from taxes, people are more likely to sign up for expensive policies and consume more health care. The head of the Congressional Budget Office has made clear that taxing insurance plans would be one of the few ways to get his stamp of approval that reform will truly “bend the curve” of the country’s soaring health care costs.

But even as consensus grows, others warn that the effect of taxing health benefits is being greatly overstated. They concede there is a case for limiting the tax exemption — to raise money for universal coverage, as well as to equalize the status between employer benefits and individual coverage bought with after-tax dollars — but say that move is not some kind of golden key for bringing spending under control.

“The waste in our system is enormous, but it’s not the consumer driving that waste. To the extent that consumers ask for care, it’s because they’ve been told they need it by providers,” said Harvard health policy professor Donald Berwick.