It depends on the type of disability.
Supplemental security income (SSI) payments aren't taxable.
For the majority of people, Social Security Disability (SSDI) benefits are not taxable. This is true for people who have income in addition to disability benefits as well as those who do not.
If you are retired on disability, benefits you receive under your employer's disability retirement plan are considered earned income until you reach minimum retirement age.
However, payments you received from a disability insurance policy that you paid the premiums for are not earned income.