Early this month, Senator Marco Rubio introduced the Economic Security for New Parents Act, a proposal for paid family leave that is modeled after one that I developed. The idea is to offer new parents the option of collecting Social Security benefits for at least two months in return for deferring their retirement age for the period of time necessary to offset the cost.

Many policymakers have opposed giving parents this option. Senator Kirsten Gillibrand argued that it presents a “false choice” between parental leave and retirement. Senator Sherrod Brown stated that it’s “not paid family leave at all” but instead “robbing from your retirement.” They would prefer to fund leave through a “low cost” payroll tax.

However, a payroll tax would not magically lower the cost of a federal parental leave program. It would “rob” from every paycheck, and workers would have no choice (not even a “false” one) but to pay it. The tax might seem small, but it would cost thousands of dollars over the course of a lifetime — otherwise it would not sustain the program.

Although neither the Social Security proposal nor a payroll tax can reduce the cost of parental leave for workers, both approaches can make leave affordable for workers who would otherwise have to take unpaid leave to care for a new child. And the Social Security proposal has some added advantages: It is less likely to displace employer-provided leave, and it is a pragmatic solution, one that does not require a new tax, to a problem that affects most American families.