20% is the mandatory withholding but you can request more. If you are under age 55* then there will be a 10% early distribution penalty in addition to the normal tax. 34% should cover both the tax and penalty.
(* The normal under age 59 1/2 penalty is waived if you leave employment with the plan sponsor and are age 55 or more.)
{edited to correct age 55 typo]
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
