Under current law, less than 30 percent of the benefits paid by the Social Security and Railroad Retirement programs is subject to the federal income tax. Recipients with income below a specified threshold pay no taxes on those benefits. Most recipients fall in that category, which constitutes the first tier of a three-tiered tax structure. If the sum of their adjusted gross income, their nontaxable interest income, and one-half of their Social Security and Tier I Railroad Retirement benefits exceeds $25,000 (for single taxpayers) or $32,000 (for couples filing jointly), up to 50 percent of the benefits are taxed. Above a higher threshold--$34,000 for single filers and $44,000 for joint filers--as much as 85 percent of the benefits are taxed.
By contrast, distributions from defined-benefit plans are taxable except for the portion that represents the recovery of an employee's "basis"--that is, his or her after-tax contributions to the plan. In the year that distributions begin, the recipient determines the percentage of each year's payment that is considered to be the nontaxable recovery of previous after-tax contributions, based on the cumulative amount of those contributions and projections of his or her life expectancy. Once the recipient has recovered his or her entire basis tax-free, all subsequent pension distributions are fully taxed. (Distributions from traditional defined-contribution plans and from individual retirement accounts, to the extent that they are funded by after-tax contributions, are also taxed on amounts exceeding the basis.)1
This option would treat the Social Security and Railroad Retirement programs in the same way that defined- benefit pensions are treated by defining a basis and taxing only those benefits that exceed that amount. For employed individuals, the basis would be the payroll taxes they paid out of after-tax income to support those programs (but not the equal amount that employers paid on their workers' behalf). For self-employed people, the basis would be the portion (50 percent) of their self- employment taxes that is not deductible from their taxable income. Revenues would increase by $184 billion from 2012 through 2016 and by $438 billion from 2012 through 2021.
An argument in favor of this option concerns equity. Taxing benefits from the Social Security and Railroad Retirement programs in the same way as those from defined-benefit pensions would make the tax system more equitable in at least two ways. First, it would eliminate the preferential treatment given to Social Security benefits but not to pension benefits--a preference that is minimal for higher-income taxpayers but much larger for low-and middle-income taxpayers. Second, it would treat elderly and nonelderly taxpayers with comparable income the same way. For people who pay taxes on Social Security benefits under current law, the option could also simplify the preparation of tax returns because the Social Security Administration--which would have information on their lifetime contributions and life expectancy--could compute the taxable amount of benefits and provide that information to beneficiaries each year.
This option also has drawbacks. A greater number of elderly people would have to file tax returns than do so now. People with incomes below $44,000, including some who depend solely on Social Security or Railroad Retirement for their support, would have their taxes increased by the greatest percentage. In addition, raising taxes on Social Security and Railroad Retirement benefits would be equivalent to reducing those benefits and could be construed by some retirees--as well as people nearing retirement--as violating the implicit promises of those programs, especially because the option would provide no opportunity for them to adjust their saving or retirement strategies to mitigate the impact. Finally, calculating the percentage of each recipient's benefits that would be excluded from taxation would impose an additional burden on the Social Security Administration.