I made an early withdrawal on my 401k in early 2017. I didn't withhold taxes, because I didn't earn much income in 2016 (lived off savings as I left my salary job in 2015 to start new business). Should I still make estimated tax payments to reach 20% withholding throughout the year? Or will my tax be lower given my low income level in 2016?
If you meet the conditions in the second Answer, you don't have to make any estimated payments, since there will not be a penalty.
The 10% early penalty is fixed ; that is a separate issue.
BUT, estimated payments will spread out your tax burden.