The Federal Insurance Contribution Act, or FICA, is a federal program funded through tax payments. Your contribution pays for benefits other citizens receive from the fund. You also earn credits from the taxes you pay in, which helps make you or your dependents eligible for future program payments. The difference between FICA and FICA-Med is that one deduction goes toward the program's cash benefits fund, and the other goes toward its medical benefits fund.
The FICA number you see on your paycheck is your Social Security tax deduction. You pay half of your Social Security taxes through a mandatory payroll deduction, and your employer pays the other half. These taxes pay Social Security benefits to retirees, supplemental Social Security Income payments to low-income disabled citizens and any benefits due to eligible survivors.
The FICA-Med deduction is just for Medicare tax. Similar to Social Security taxes, you pay half from your wages and your employer pays the rest. Taxes collected for Medicare taxes fund the health care program for retired and elderly citizens. This paycheck deduction is also mandatory even if you don't anticipate getting Medicare yourself.
Both taxes are based on gross earnings before any other deductions or taxes are subtracted. The total Social Security due from individuals is 12.4 percent, so your portion of your FICA deduction is 6.2 percent of your gross wages. The total Medicare tax due is 2.9 percent, which makes your FICA-Med deduction 1.45 percent.
Social Security taxes are subject to maximum wage limits each year. As of 2015, the maximum was $118,500. No Social Security taxes are collected on earnings over that limit. Medicare taxes have no wage base limits, so you'll always have Medicare taxes deducted. However, if you earn more than $200,000 per year, your employer will deduct an extra 0.9 percent Medicare tax on wages over this amount.