Is it necessary to have Social Security card to get supplemental income or disability or is the number enough?

It is not necessary to have a physical Social Security card to apply for Supplemental Security Income (SSI) or Social Security Disability Insurance (SSDI); however, you do need your Social Security number. You can provide your number in the application process, and the Social Security Administration (SSA) can verify your identity and eligibility without the card. It's advisable to have the card for personal records, but it's not a strict requirement for the application.