The U.S. Social Security Administration has published a fact sheet for the 2018 Social Security rates and cap. For both employers and employees, the rate for the Social Security portion (OASDI) remains 6.20%, and the rate for the Medicare portion remains 1.45%. For the self-employed, the OASDI rate remains 12.4% and the Medicare rate remains 2.9%. The taxable earnings cap for OASDI is increased from USD 127,200 to USD 128,700. No cap applies for Medicare. Click the following link for the 2018 Social Security fact sheet.