Eligibility for benefits is earned through workers’ payroll tax contributions. As noted, nearly all workers in the United States are required to contribute to the Social Security program. All citizens and those with legal alien status who work and pay contributions for the required number of quarters (forty, that is, ten years) are eligible for pension benefits when they reach the minimum retirement age; survivor and disability benefits also require certain minimum work credits. To qualify as disabled, individuals must have a prolonged or terminal condition and may not earn more than $810 per month.

Under certain circumstances, a worker’s spouse, children, and parents may qualify for Social Security benefits based on the worker’s contribution history. Unmarried children under age eighteen (or over eighteen if severely disabled), elderly spouses, and spouses caring for young children are generally eligible for benefits if a worker retires, becomes disabled, or dies. The elderly parents of a deceased worker may be entitled to survivorship benefits if they were financially dependent on the child for at least half their support.

(See SSA publications "Understanding the Benefits" and "Disability Benefits".)