Social Security is the US federal program providing retirement, disability, and survivor benefits funded through payroll taxes. Your monthly benefit is determined by your Average Indexed Monthly Earnings (AIME) — a 35-year average of your inflation-adjusted earnings — and the age at which you claim. The SSA applies a progressive Primary Insurance Amount (PIA) formula that replaces a higher share of income for lower earners, ensuring meaningful support across all income levels. Understanding how the formula, your Full Retirement Age, and early/delayed retirement credits interact is essential for making an informed claiming decision — one of the most consequential financial choices most Americans make.