If I retire at 50, can I use the Rule of 55 to reach my 401(k) penalty-free?

No. The Rule of 55 only helps if you separate from your employer in or after the year you turn 55; retiring at 50 is too early to use it. To access retirement-account money at 50 without the 10% penalty, you would instead rely on other tools: withdrawing Roth IRA contributions (always penalty-free), spending from a taxable brokerage account, building a Roth conversion ladder started years earlier, or setting up a 72(t) SEPP plan on an IRA. Many people who retire in their early 50s bridge the years from 50 to 55 with taxable savings, then let the Rule of 55 or 59.5 access kick in later. Because the age windows for each method differ, mapping out which account funds which years is one of the most important parts of an early-retirement plan.