Having "Retirement plan" checked in box 13 of your W-2 might require an amended return.
On the tax return that you filed, do you have an IRA deduction on Schedule 1 line 20? If not, if Schedule 1 line 20 is blank or you do not have Schedule 1 at all, then checking "Retirement plan" will not affect your tax return, so there is nothing to amend it for.
If you do have an IRA deduction on Schedule 1 line 20, then depending on your filing status and your Adjusted Gross Income (AGI), checking "Retirement plan" might reduce or eliminate your IRA deduction. In that case, you would definitely have to file an amended return. Since you have already made the IRA contribution, if your IRA deduction is reduced or eliminated that means that part or all of your IRA contribution becomes nondeductible. So in addition to reducing or eliminating the deduction, you would have to include Form 8606 in your amended return.
Yes, you should amend your return to reflect that you participate in a retirement plan so you can be properly credited for deductions, taxes, etc.
The “Retirement plan” indicator in Box 13 shows whether an employee is an active participant in your company’s plan. If this box is checked, it lets the recipient know that depending on their filing status and modified adjusted gross income, they may not be entitled to a full deduction for their traditional IRA contributions.
Having "Retirement plan" checked in box 13 of your W-2 might require an amended return.
On the tax return that you filed, do you have an IRA deduction on Schedule 1 line 20? If not, if Schedule 1 line 20 is blank or you do not have Schedule 1 at all, then checking "Retirement plan" will not affect your tax return, so there is nothing to amend it for.
If you do have an IRA deduction on Schedule 1 line 20, then depending on your filing status and your Adjusted Gross Income (AGI), checking "Retirement plan" might reduce or eliminate your IRA deduction. In that case, you would definitely have to file an amended return. Since you have already made the IRA contribution, if your IRA deduction is reduced or eliminated that means that part or all of your IRA contribution becomes nondeductible. So in addition to reducing or eliminating the deduction, you would have to include Form 8606 in your amended return.
Perfect, yes I only had my 401-K for this year so did not have a schedule 1 - so it looks like I wouldnt need to amend my return correct?
Yes, that is correct. As long as the original W-2 had the information from your 401(k) in Box 12 with Code D, you do not need to amend your return.
Since you did not contribute to an IRA, the information that changed on your corrected W-2 will not change any information that you originally filed. Keep the corrected W-2 for your records.