401(k) plans allow you to begin withdrawing money, without penalty, after age 59½. However, there is a 10% penalty tax on withdrawals made before age 59½ (if you don't roll it over) from your 401(k) plan, unless the distribution is made under one of the limited circumstances allowed by law. That is, there is a penalty for taking your money "too soon."
Some Exceptions to the 10% Early Withdrawal Penalty for 401(k) Plans
The 10% early withdrawal penalty does not apply to these situations:
IMPORTANT NOTE: Using your retirement plan savings for non-retirement purposes should always be your last resort.
For more information, see the section Distributions Over Your Life Expectancy.