Yes, over contributing to your 401(k) is considered an "Excess Salary Deferral".
No, you should not create a mock Form 1099-R.
You can report the refund of the excess contributions to your 401K on Line 7 of your 2017 Tax Return without a Form 1099-R by following these steps:
- Click on the "Federal Taxes" Tab
- Click on the "Wages & Income" Tab
- Click on "I'll choose what I work on"
- Scroll down to "Less Common Income"
- Select "Miscellaneous Income" and click Start or Update
- Select "Other income not already reported on a Form W-2 or Form 1099" and click on Start
- Answer the Question "Did you receive any other wages? Yes
- Click through the questions until you get to "Any Other Earned Income"
- Answer Yes to "Did you earn any other wages?
- Indicate "Other" as Source of Other Earned Income and click Continue
- For the description enter "2017 Excess 401K Deferrals" and click on Done
You will receive a 2018 Form 1099-R in 2019 with a code P in box 7 which you can ignore if the excess deferral is reported as suggested above. However, the earnings will be reported on a separate 2018 Form 1099-R with a Code "8" in Box 7 that should be reported on your 2018 tax return.
