How Do I Get TurboTax to Register the After-Tax Contribution to My 401K Rolled Over to Roth IRA (a so-called "Mega Back Door Roth Contribution")?

[ColoradoTaxpayer]

TurboTax is not registering my after-tax contribution to my I-401K-Regular.

My I-401K was empty.

I put $10,919 in as an "employer", after-tax, contribution.   I have an LLC with pass through taxation to me individually so I paid income tax on this amount prior to its contribution.

Now when I try to enter my 1099-R which Vanguard provided, I cannot get TurboTax to register the after-tax contribution.

On my 1099-G

1.  My Box 1 Gross Distribution is $10919

2.  My Box 2a Taxable Amount is $10919 ( Vanguard says they have to list it this way because they don't keep track of whether "Employer contributions" are post-tax or pre-tax.  Very frustrating.)

3.  Box 5 is empty (Again, Vanguard says they have to list it this way for the reason above).

4.  Box 7 is G

When I enter it into TurboTax, TurboTax asks:

1. Was this money rolled over to a Roth IRA?   I say "yes".

2.  Did I make after-tax contributions to my 401K?   I say "yes".

3.  A screen comes up asking the list the amount of the after-tax contribution?  I enter "$10,919".

But it still assesses me tax as though the rollover was of a pre-tax contribution.  

It thus appears not to be registering that the after-tax contribution should register as non-taxable in the rollover to Roth.

How do I get it to register that this is after-tax funds and thus should not be taxed again?

[dmertz]

Employers are not permitted to make after-tax contributions.  Since this was an employer contribution, its was pre-tax.

[ColoradoTaxpayer]

The IRS deems it "profit-sharing" and because the tax on profits passes through directly to me, it's after-tax. 

This strategy is called the "Mega Back Door Roth" because it is after-tax by the owner of a business without employees.

[dmertz]

The employer takes a deduction for an employer contribution, making it pre-tax.  (If the employer fails to take the deduction, that's simply a mistake on the employer's tax return.  Such a mistake does not make it after-tax.)  Employer contributions such as profit-sharing contributions are compensation to the employee on which the employee has not yet paid taxes.

As I said, employers are not permitted to make after-tax contributions.  Employer contributions that are not deductible are subject to penalty.

The taxable amount on the Form 1099-R provided by Vanguard is correct.

Mega-backdoor Roths involve after-tax employee contributions from compensation paid to the employee, not employer contributions.

[ColoradoTaxpayer]

Again, this is a pass-through entity (i.e. all income is "passed through" to the owner as income on which s/he pays tax).  There is no deduction at the entity (or employer) level.  Full ordinary income tax is paid on it by the LLC owner.

This is a common strategy for owners of pass-through entities such as LLC, S-Corp, and Partnership owners.

Please do not comment when you are unfamiliar with the topic. 

[dmertz]

I'm quite familiar with the topic.  I've added to my previous reply indicating that the mega-backdoor Roth involves after-tax employee contributions, not employer contributions.  Employer contributions are deducted on the employer's tax return (in the case of a partner in a partnership, on the partner's individual tax return as a pass-through deduction).

[macuser_22]

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Please do not comment when you are unfamiliar with the topic. 

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User @dmertz IS an expert in this area and has studied  the actual tax laws and has much more knowledge about this than do most financial institutions or tax professionals.