actually a roth 401k is exactly what one would assume. after tax retirement contributions offered by one's employer. it's a relatively new compared to traditional 401k so not many workplaces offer it. the contribution limit for roth 401k is same as traditional, but effectively higher since it's post-tax vs pre-tax.

The Pension Protection Act of 2006, signed into law by President Bush on 8/17/06, made the Roth 401(k) permanent, removing the 12/31/10 expiration date that previously was in force. (8/17/06).

 

Wow, interesting. I did not know that. Wouldn't it be called a 402a, though, since that is the IRS tax code (according to wiki at least)? It just seems a tad contradictory to include 401k in the title when the term "401k" has a specific set of tax implications.