The misguided campaign to preserve Individual Retirement Accounts with their present double exemption seems to be picking up momentum. A lot of it is coming from people who think -- incorrectly -- that the Senate Finance Committee's bill would abolish their IRAs. Perhaps the reason they think so is that some of the propaganda being disseminated by mutual funds and stock brokerages hints at it.

But the IRA would continue to be available under the Finance Committee's bill. True, the money put in it would no longer be exempt from taxation if the taxpayer is covered by a private pension plan. But the other and more important exemption, covering interest as it accumulates and compounds, would remain unchanged. As under present law, the exemption is not permanent. It runs only until the money is withdrawn from the account. But at that point, if the Finance Committee's bill is enacted, it will be taxed at rates that, for most people, will be significantly lower than the present ones.

That's the basic bargain on which this bill has been built, and it's a bargain worth making. Many tax breaks would be ended under it, and they would pay for the lower rates. But taxpayers can't have it both ways. They can't keep all their exemptions and, at the same time, hope to have the low tax rates in the Finance Committee's bill.

There's a peculiar psychology to tax breaks. People often think of them with a special warmth as something of their own, the special advantages that Congress gave them to help them in their struggles with the tax code. Perhaps it was a break for their industry, or perhaps it was encouragement for virtuous behavior -- in this case, saving for retirement. The breaks get tangled up in personal values and commitments that go far beyond their monetary worth. In contrast, a lower rate structure seems abstract and remote.

That seems to be one prominent reason for the sudden strength of the defense of the IRAs. But its defenders need to think carefully about all the other interests that want them to win. A lot of people are now trying to preserve other tax breaks that are less well known than the IRA and far less accessible, but more profitable to those who use them. If the friends of the IRA save its double exemption, they will have torn a large hole in the Finance Committee's bill. Once that hole appears, there are many tax lobbyists who will go rapidly to work to widen it. With that, it will become impossible to lower tax rates as the bill proposes. A dramatic attempt at structural reform would then peter out, and Congress would have missed a remarkable opportunity.