How do you categorize the money that comes out of your paycheck to fund Social Security? Do you consider that deduction to be a tax, or a mandatory contribution into a retirement account, or an insurance premium? For many people, the answer is a tax. That’s what I heard from the majority of readers who responded to my most recent column, “3 Ways to Fix Social Security and Medicare.” It’s an understandable view. After all, the Social Security payroll deduction is commonly referred to as a FICA tax. (What’s FICA, you ask? FICA is the acronym for Federal Insurance Contributions Act.) And because it’s called a tax, these readers think that Social Security reforms should focus on making wealthier wage earners pay more into the system. Making all wage income subject to payroll taxes would solve between 75% and 80% of the system’s funding shortfall. I don’t agree with this approach, as I’ll explain. Still, these readers have plenty of company, including some leading critics of Social Security, who argue that payroll taxes are less progressive than the federal income tax. Everyone who works in a job that is covered under Social Security rules pays the same rate: 7.65% of their earned income up to an annual ceiling of $117,000 in 2014; the level is increased annually for inflation. Employers pay another 7.65%. (These totals include 6.2% for Social Security and 1.45% for Medicare.) The way Social Security’s benefits are designed, at this year’s $117,000 income level, you receive the maximum credit—those earning higher salaries would not qualify for any more benefits. That’s why requiring wealthier people to pay even higher taxes without any additional income would break the implicit bond between your contributions and the benefits you may receive. And the move would certainly undermine support for the program. Whatever Social Security lacks in progressive taxation it more than makes up for in the benefits it pays out, which are heavily weighted toward lower earners. Here’s how: The program breaks a person’s lifetime earnings history into three dollar segments that are divided by so-called “bend points.” Adjusted annually for inflation, the bend points are $816 and $4,917 in 2014. For the first $816 of your lifetime average monthly Social Security earnings, 90% are credited toward your monthly benefits. Between $816 and $4,917 in earnings, only 32% are applied to benefit entitlements. And for average monthly lifetime earnings above $4,917, only 15% are counted in determining your monthly retirement benefit. Add it all up, and lower-income retirees wind up with Social Security benefits that make up a much higher portion of their pre-retirement incomes, typically 50% or more, than wealthier households, which may receive less than 20% of income from these benefits. That payout usually exceeds the amount that lower-income beneficiaries put in, according to research by the Urban Institute, a Washington non-profit. (That’s notwithstanding the mantra of groups pushing to protect and even expand Social Security: “It’s Your Money; You Paid for It.”) The difference between the amount lower-income households pay and the benefits they eventually receive comes out of the pockets of higher-paid workers. Of course, balancing Social Security by jacking up payments by wealthier earners feels good to many people and may even seem fair. But let’s try a thought experiment. What if Social Security worked like a 401(k) plan—you contributed a percentage of your salary, often matched by an employer contribution, and the account grows tax-deferred until you withdrew it at retirement. If I put $5,000 a year into my 401(k), but you earn more and can put $20,000 into yours, is this unfair? Should some of your contributions be placed instead inside my 401(k) simply because you make more money? If you think Social Security is different from a 401(k), then you must also be viewing it at least in part as a welfare program that should be taking assets from the top 10% and distributing them to the other 90%. I don’t share this view, but I would support boosting the earnings ceiling by a hefty amount. Payroll taxes used to catch 90% of all wages. After years of lopsided wage gains by wealthier persons, only a little more than 80% of wages is currently subject to payroll taxes. It would be a reasonable move to restore the original level of taxation. Even so, Social Security’s primary mission is to provide retirement security—a safety net that would help keep aging Americans out of poverty. It was not supposed to be a tax collector. That’s why I think the best way to look at the program is as a form of insurance for longevity, rather than an investment that should give you a better-than-break-even rate of return. So if you believe that wealthy people should pay higher taxes, change the tax code. Don’t look to Social Security to do this work for you. The Committee for a Responsible Federal Budget, a Washington non-profit, has a Social Security calculator showing reform options and their impact. If you use this tool, we’d like to hear how you would reform Social Security, so please share your ideas. We’ve all got a stake in this. Philip Moeller is an expert on retirement, aging and health. He is an award-winning business journalist and a research fellow at the Sloan Center on Aging & Work at Boston College. Reach him at firstname.lastname@example.org or @PhilMoeller on Twitter.