There is a growing movement to eliminate the wage cap on Social Security taxes while capping benefits. The argument, often from the center-right, is that Social Security is insolvent and that “tough” choices are needed to save it. But this moves the system in exactly the wrong direction.

One of the better features of Social Security is that it has never been purely redistributive. It has also functioned, in part, as a forced-savings program. The Social Security Administration itself emphasizes that benefits depend on earnings history: earn more, retire with more. Why do some people receive large Social Security checks? Because they paid a lot more into the system.

Eliminating the wage cap while capping benefits weakens, and in the limit destroys, that connection. It turns Social Security away from forced saving and toward retirement welfare financed by a broader tax on earnings. That is a bad idea.

The problem is not just that this creates another welfare program. It also worsens marginal incentives. A tax that buys you a claim on future benefits is not the same as a pure tax. Suppose 10 percent of your salary goes into a 401(k). That reduces current consumption, but it is not simply money lost to the state. You receive an asset in return. It is closer to a purchase than to a tax–a reason to work more not a reason to work less.

Social Security is not a personal retirement account, but it does contain that logic. There is a connection between taxes paid and benefits received. To the extent that workers understand that connection, the payroll tax is less distortionary than an ordinary tax of the same size. Part of what workers pay is offset by the expectation of future benefits.

Gut that connection, however, and the tax becomes more distortionary even if total taxes paid and total benefits received stay the same. The averages can remain unchanged while the marginal incentives deteriorate. Once additional taxes no longer generate additional benefits, the system looks much more like a straight tax on work.

A much better reform would move in the opposite direction: strengthen the link between contributions and benefits. Make Social Security more like what many people already think it is—an individual account that accumulates benefits over time. The stronger that link, the lower the effective tax wedge.

This would also improve the politics of the system. A welfare program invites zero-sum conflict: my benefit comes at your expense. A claim-based system is less divisive. It ties benefits more clearly to contributions and makes rising prosperity good for everyone. In that kind of system, we can all become richer—including low-wage immigrants—without treating retirement policy as a fight over who gets to pick whose pocket.

Addendum: James Buchanan first made these points here. John Cochrane gets the economics right, of course.