Share your insights or perspective on the financial matter presented in the input.

How to calculate tax amounts withheld on mixed pre-tax and Roth 401(k) contributions, and match?
Its easier than that: employer matching contributions are  always pre-tax. While your contribution is split between the pre-tax and the Roth post-tax parts, matching contributions are always pre-tax. Quote from the regulations I linked to: For example, matching contributions are not permitted to be allocated to a designated Roth account. So the tax you pay is only on the Roth portion of your contribution. One of the reasons for that is the complexity you're talking about, but not only. Matching is not always vested, and it would be hard to determine what portion to tax and at what rate if matching would be allowed to go to Roth.