I am sole-proprietor and have 1099-NEC income that I contributed to solo-401k in Dec 2024. It will be Excess contribution since I wasn't supposed to contribute.

[ThoengB88]

For easy numbers, let's say, I have 1099-NEC box 1 for $10k. From this $10k, I contributed $9k to my Solo 401k. Excess contribution $9k will be returned to me from my brokerage before filing tax is $9000.50. (with $0.50 interest). In Turbotax, for my 1099-NEC income, I need to put $10k because it is what is said on the 1099-NEC form. I read solutions for similar situation (but for W2) that they have to add this excess contribution as "Other income not already reported on a form w2 or form 1099". But, for my situation as a 1099, the excess contribution of $9k is already included in the 1099-NEC. Could you please advise on how to report this Excess contribution (1099-NEC income) on my 2024 tax? Also, if there is interest (most likely less than $1), where should I report, too? Thanks in advance!

[RobertB4444]

The 10K is just reported as income.  You're doing your schedule C using that 10K.

The return of the 9K and change is going to be entered on a substitute 1099-R that you're going to create.  The 1099-R is a form that you will receive in January of 2026 for the 2025 tax year but since you're going to enter it on your 2024 tax return you will be able to ignore it when you receive it next year.

In the wages and income section of your federal return you will scroll down to the section marked 'Retirement Plans and Social Security' and click start next to the one marked "IRA, 401K, Pension Plan Withdrawals (1099-R)".  Then, when it asks about your 1099-R you'll say "I'll type it in myself".  

On the next screen you'll tick the box for 1099-R.  You'll also tick the box that says "I need to prepare a substitute 1099-R".  Then you'll enter the total amount that you received ($9000.50 in your numbers) into box 1 of the 1099R and the taxable amount ($0.50 in your numbers, which counts as a dollar for IRS purposes) in box 2a.  The only other information that you have to enter is code 8 in box 7.  Code 8 indicates that it is the return of an overcontribution.  Do not check the IRA box.

That's it.  The reporting will be done.  As I said before you will still get the real 1099-R next year but when you do you can just file it since it was already reported.

@ThoengB88