Thus, the self-employed individual must pay the IRS both the employee and the employer halves of Social Security/Medicare tax. Self-employed workers pay twice as much as either an employee or an employer pays for FICA taxes. The pressure a 15.4 percent flat tax puts on self-employed pushes many self-employed into the IRS deductions trap. Martha's story. Recently a friend who is a nationally known artist and sculptor went in to sign up for Social Security.