Can working part-time in early retirement really make a big difference?

Yes – even modest part-time income has an outsized effect, especially in the first years of retirement. Earning $15,000–$25,000 a year means you withdraw that much less from your portfolio while it's still recovering or compounding, which directly counters sequence-of-returns risk. It can also delay Social Security so your eventual check is larger, provide health coverage if the job offers benefits before age 65, and deliver social engagement and structure that many retirees miss. The main caution is that if you claim Social Security before full retirement age, the earnings test can temporarily withhold benefits above an annual limit (though you get it back later). For many people, a few years of light work bridges the gap between an early retirement date and full financial security.