A 401(k) can be one of your best tools for creating a secure retirement. It provides you with two important advantages. First, all contributions and earnings to your 401(k) are tax-deferred. You only pay taxes on contributions and earnings when the money is withdrawn. Second, many employers provide matching contributions to your 401(k) account which can range from 0% to 100% of your contributions. The combined result is a retirement savings plan you cannot afford to pass up.