20% Withholding...Every Time You Withdraw Money From your 401k or 403b Employer Plan
The IRS has a mandatory withholding of 20% each time you take money from your employer plan.
Your IRA does not have a mandatory withholding of 20%... It's still taxable but the IRA does give you the flexiblility to have a different tax withheld. You could do 10, 15 or even zero percent. Talk with your tax advisor...the IRA will let you indicate the tax withholding.
If you're over 70 1/2 your MRD is treated different-you can elect not to have any taxes withheld. Of course the MRD is still taxable...