The statement that is true of Social Security but not Medicare is:
Money withheld from your paycheck is used to pay benefits to people who are collecting them now.
While both programs are funded through payroll taxes and provide benefits to retirees and people with disabilities, the structure of how funds are used differs. Social Security operates on a pay-as-you-go basis, where current workers' contributions pay for current beneficiaries. Medicare, however, is primarily an insurance program that helps cover healthcare costs for eligible individuals, rather than directly redistributing payroll taxes in the same manner as Social Security.