The earliest an individual can withdraw funds from a 401(k) without penalty is age 55, as of 2015, according to About.com. To make withdrawals at 55, an individual must terminate employment no earlier than the year he turns 55 and leave the funds in the 401(k) plan.
If an individual terminates employment earlier than age 55 and waits until age 55 to take a withdrawal, the withdrawal is subject to a 10 percent early withdrawal penalty tax. If an individual rolls over a 401(k) to a traditional IRA, the earliest that funds can be withdrawn without penalty is age 59 1/2, as of 2015. Required minimum distributions must be taken from a 401(k) once an individual reaches age 70 1/2, states About.com.