The rules for a 401(k) withdrawal are available on the website of the Internal Revenue Service. The website lists the three conditions necessary for a person to make withdrawals from a 401(k).
Savers with a 401(k) can make withdrawals as either a lump-sum on a irregular basis or as a regularly scheduled payment, such as an annuity, according to the IRS. The IRS also gives information on required withdrawals based on the specifications of individual 401(k) plans and the obligations of the plan administrator to obtain consent. In addition, the site gives general conditions required for hardship withdrawals, such as medical exceptions and tuition payments.