Social Security Disability Insurance (SSDI) is funded through payroll taxes, specifically the Federal Insurance Contributions Act (FICA) tax. Both employees and employers contribute to the funding of SSDI through these payroll taxes. The FICA tax is divided into two parts: the Social Security tax and the Medicare tax. The Social Security tax portion goes towards funding various Social Security programs, including SSDI. As of 2024, the FICA tax rate for Social Security is 6.2% for both employees and employers, resulting in a total of 12.4% contribution for each employee's wages. It's important to note that self-employed individuals are responsible for paying the entire 12.4% themselves. Therefore, the responsibility for funding Social Security Disability Insurance falls on both employees and employers through the FICA tax contributions. The funding for SSDI primarily comes from payroll taxes, with both employees and employers contributing through the FICA tax.