Rollover
Moving money from one retirement account to another, such as an old 401(k) to an IRA, without paying tax on it.
In a direct rollover, the old plan sends the money straight to the new account, so no tax is withheld. If the plan pays you instead, it must withhold 20%, and you have 60 days to deposit the full amount, including that 20%, to avoid tax.
Traditional money should go to a traditional IRA or plan, and Roth money to a Roth account. Moving traditional money into a Roth IRA is allowed but taxed as income that year.
Example
If you roll $18,000 into an IRA directly, all $18,000 arrives. If the plan pays you, you get a check for $18,000 × 80% = $14,400.