When answering the question, "How much did you receive in disability benefits?," include only untaxed disability benefits from entities other than the Social Security Administration (SSA).
This means:
Do not include Social Security Disability Insurance (SSDI) nor Supplemental Security Income (SSI) - These are both supplied by the SSA and do not count on the FAFSA®.
Do count disability benefits/pensions paid by an employer, if they are untaxed.
Do not count disability benefits/pensions paid by an employer, if they ARE taxed. (In that case, the relevant amount would already be part of your Adjusted Gross Income. The FAFSA® is trying to determine if you got any more income/benefits above and beyond that amount.)