What is the earliest age I can retire?

Age 55: if you leave an employer during or after the year you turn 55, withdrawals from that employer's qualified plan, such as a 401(k), are not subject to the 10% additional tax. The age is 50 for public safety employees in governmental plans. This rule does not apply to IRAs.

Age 59 1/2: withdrawals from IRAs and workplace plans are free of the 10% additional tax. Regular income tax still applies to pre-tax money. At any age, a series of substantially equal periodic payments can also avoid the additional tax, from IRAs or plans, but the payment schedule is strict.

Age 62: the earliest age for Social Security retirement benefits. If your full retirement age is 67, the check at 62 is 70% of the full amount, for life.

Age 65: Medicare eligibility. The sign-up window is 7 months, starting 3 months before the month you turn 65. Missing it can mean a late enrollment penalty for as long as you have Part B.

Example: someone who stops working at 58 can draw from the 401(k) at the job they just left, but not from an IRA without the 10% additional tax for another year and a half. Social Security is 4 years away and Medicare 7 years away, so savings must cover both living costs and health coverage until then. The earliest age you can retire is really the earliest age your savings can carry that gap.