If I take an early withdrawal from my 401k, how will I be penalized come tax season?

This should answer your question:

401k Penalty (http://www.401kpenalty.net/)

PolitiFact | No. 508: Allow penalty-free hardship withdrawals from retirement accounts in 2008 and 2009 (http://www.politifact.com/truth-o-meter/promises/promise/508/allow-penalty-free-hardship-withdrawals-from-retir/)