Do I need documentation to prove which % of my Roth 401K contributions are from me the employee (not taxed on withdrawal) vs. the employer (taxed on withdrawal)?

[nhfox100]

If a Roth 401K has 100K in deposits (50K employee, 50K employer), I don't understand how the calculation works for taxing part of this at withdrawal (i.e. the employer contributed portion).

[Opus 17]

Are you sure the money is going into the same account? I am contributing to a Roth plan and the pretax employer match is being contributed into a separate pretax account.

As far as I know, it’s illegal for the employer to put pretax money into a designated Roth account. Please double check with your HR department and your 401(k) custodian.

[nhfox100]

There are two accounts that I have like this. (1) through former employer (COVID-19 withdrawal and later rolled over) and (2) through a current employer. Both have funds that are not separated, as I am able to put 100% of the money into the same equity. I can check with my current employer for situation #2, but how can I get an answer on #1? Thank you

[dmertz]

The employer contributions go to your traditional account in the 401(k), not to the Roth account.

You can end up with all of the money in the Roth account only if the 401(k) plan allows In-plan Roth Rollovers (or if the employer makes no contributions).  An IRR is a taxable rollover from the traditional account to the designated Roth account in the same 401(k).  An IRR is reported on a Form 1099-R with code G in box 7 and the taxable amount in box 2a.

The 401(k) plan administrator must keep track of everything so that it can determine the taxable amount of any distributions.

[Opus 17 · Accepted solution]

@nhfox100 

When I say “account “, I don’t mean two different plan trustees. I mean that all my funds are at TIAA, but that when looking specifically at the TIAA website, I have two separate accounts at TIAA, one of which is traditional pretax and one of which is the Roth option.  You might have money at Fidelity from one employer and T. Rowe Price from another employer, but within the account managed by your current employer, there must be separate pretax and Roth option accounts.  Or, as @dmertz  indicates, your employer could be making the pre-tax deposit, and then doing an immediate in-plan Roth rollover, which is taxable to you at the end of the year.

[nhfox100]

Thank you all. Somehow I converted everything to a Roth IRA and Fidelity says it’s approved. I must have done the conversion at some point and either I already paid the tax or I’m on the hook for it sometime next year