Yes, you will need to amend.
Box 13 Retirement plan is required to be marked correctly by the employer and the IRS uses this to determine if you are eligible for a deduction for a traditional IRA contribution if your modified AGI is above certain limits base on your filing status.
You may need to amend your return if you received a tax form after you have already filed your taxes.
However, wait until your tax return has been either accepted or rejected by the IRS first. If rejected, then simply log back into your account and add the corrected W-2 information.
If it has been accepted then:
and are due a refund, it will be best if you first wait to receive your current refund before you amend. Please note: A Form 1040X, Amended U.S. Individual Income Tax Return can take up to 16 weeks to process once the IRS receives it.
After you have received your refund (or are not expecting one), please read this TurboTax FAQ about amending your 2018 tax return: How to amend (change or correct) a return you already filed.
What if I had no Traditional IRA deductions? It does not affect my refund. Can I disregard?
When you say that it does not affect your refund, have you already entered it to see? I have to admit that if you made no retirement contributions of any kind, it's difficult to see how it would make a difference.
I suggest this. Write a note to yourself that you received the corrected W-2, that the only change was the box 13 retirement checkmark, and that because it made no difference to your return, you decided not to amend the return. Put this in your permanent tax file in case anyone ever asks.
IMHO, the IRS is so busy with stimulus payments, daily tax law changes, issuing refunds, and dealing with millions of tax returns from 2019 and 2020 that are in manual processing queues that I don't think it needs an amended return that doesn't actually change anything.
Tom,
Thank you for sharing your expertise. I'm in this situation as well. What would be the reason on Schedule X form? I'm leaning towards "M - Other" then add extra notes that employer issued a corrected W2 where Box 13 (retirement plan) is checked. Any thoughts?
Check all that apply:
a Protective claim for refund
b Reservation source income adjustments
c Pass-through entity adjustments
d Federal audit and/or adjustments
e FTB audit contact
f NOL carryback See instructions
g Error on original return
h Credit adjustment
i Earned income tax credit
j Disaster loss
k Military HR 100
l Informal claim
m Other
2 Provide further explanation of reason(s) for amending below If needed, attach a separate sheet that includes your name
I forgot to add that checking the retirement plan did not affect both Fed and State refund or tax dues.