After tax contributions are not taxed, but the earnings on those contributions are taxed. I found good information here: www.nytimes.com
Is There A 10% Early Withdraw Penalty From 401k After-tax Contributions?
Is there an early withdraw penalty by taking an after tax withdraw not including interest from your 401K before your fifty-nine and a half
I don't know what you mean by "after-tax contributions Yes there is a 10% penalty for early withdrawal from a 401K.