Roll over an old 401(k) directly to avoid the 20% withholding
Added
When you move money out of a former employer's plan, ask the plan administrator to send it straight to your new plan or IRA (a direct rollover) instead of paying it to you. If a check is paid to you, the plan must withhold tax, and you have 60 days to deposit the full amount, including what was withheld, to keep it tax-free.
The result
Result: IRS: a retirement plan distribution paid to you has mandatory 20% withholding, while a direct rollover to another plan or IRA has no withholding.
Note: Not tax advice. Rules change and depend on your situation; confirm with the IRS or a tax professional.
Source
IRS: Rollovers of retirement plan and IRA distributions (opens the original source in a new tab). Check it for the latest numbers before you act.