The Rule of 55 explained

Most early-retirement strategies rely on bridging income between when paychecks stop and when penalty-free retirement-account access kicks in. Without the Rule of 55, you wait until 59½. That means a 55-year-old retiree needs 4½ years of bridge funding from somewhere else (taxable brokerage, Roth contributions, deferred compensation, part-time work). With the Rule of 55, those 4½ years are funded by the 401(k) itself, penalty-free.

The difference can be hundreds of thousands of dollars in flexibility. Without the rule, an early retiree often over-saves in taxable accounts "just to bridge the gap." With it, the 401(k) can carry more of the load, freeing other savings for other purposes.

The exact wording of IRC §72(t)(2)(A)(v): distributions are penalty-free if made after separation from service in or after the year the employee attains age 55. The phrase "in or after the year" matters. If you separate in December at 54 and turn 55 in January, the rule does not apply even though you reach 55 the next month. If you separate in January at 54 with a birthday later that calendar year, the rule does apply because the calendar year is the year you turn 55.

The rule applies only to the 401(k) or 403(b) plan of the employer you separated from. It does not apply to IRAs. It does not apply to old 401(k)s at previous employers, only the current one at separation. If you have a 401(k) at a previous job, you have two choices: leave it there and live with the 59½ rule, or roll it into your current employer's 401(k) before separating so the Rule of 55 covers the combined balance.

Common trap: rolling the 401(k) to an IRA to "consolidate" or get better investment options. Once the money is in an IRA, it's subject to the IRA early-withdrawal rules, not the 401(k) rules. The Rule of 55 evaporates. Stay in the 401(k) until you no longer need penalty-free access, then roll.

Bonus rule: 457(b) plans. Government and certain non-profit employers offer 457(b) plans that allow penalty-free distributions at any age after separation. There's no Rule-of-55 cliff; separation alone is enough. If you have both a 401(k) and a 457(b), tick both boxes in RetireWise and the simulator routes early withdrawals accordingly.