You need to include the excess contribution on your 2018 Tax Return. You will
receive a Form 1099-R in 2019 with a code P in box 7 which you can ignore if the excess deferral is reported as
suggested below. However, the earnings (if any) will be reported on a
separate 2019 Form 1099-R with a Code "8" in Box 7
that should be reported on your 2019 tax return.
Note: You do not have the option to report the income on your 2019 Tax Return, it must be included on your 2018 Tax Return.
You should include the payments made with your extensions on your Tax Return by following these steps:
- Search for the term estimated tax payments
- Select the Jump to link.
- Choose Start next to the type of estimated tax payment you'd like to enter.
To include the excess contribution to your 401(K) on line 1 of your 2018 Form 1040 by following these steps:
- Open your return
- 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" and
click "Show More"
- 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
"Continue" 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 "2018 Excess 401K Deferrals" and
click on "Done"
