I took out a loan on my 401k. I am actively repaying on the loan. Do I have to pay the additional 10% for early withdrawl?

[VolvoGirl]

Did you get a 1099R for it?  If you got a 1099R then it was not a loan or  you didn't pay it back and it is now taxable.   What code is in box 7 on the 1099R?    

[Opus 17 · Accepted solution]

A loan is not a withdrawal and no part of the loan is taxable or subject to penalties, as long as the loan is in good standing.

If you stop making repayments (such as because you leave the company) the outstanding balance is treated as a distribution and is subject to tax and penalties at that time.