A dependent is a person you support financially who qualifies under IRS rules — either as a qualifying child or a qualifying relative. Claiming a dependent can unlock valuable tax benefits like the Child Tax Credit, dependent care credit, and a potential head of household filing status. Each person can only be claimed as a dependent on one return per year. Dependents must have a Social Security number, ITIN, or adoption taxpayer number. Use the IRS "Whom Can I Claim as a Dependent?" tool when unsure.