Yes, you can amend your 2020 tax return. Student loan interest is one of the adjustments to income that will reduce your Adjusted Gross Income AGI and taxable income. Depending on the amount, it may likely increase your refund.
Since you have already submitted your tax return, you will have to wait when the IRS processes your return starting from February 12, 2021. You cannot return to the program to make any changes before that.
If your return got rejected for whatever reasons, you can return to the program to enter the student loan interest along with other changes. You do not need an amendment 1040-X.
If your return has been accepted, you will have to amend your return by filing a form 1040X. You should not try to amend your return until it has been fully processed and you have received your refund or your payment has cleared.
Beginning with the 2019 tax year, you can e-file amended tax returns. If you used TurboTax to prepare Form 1040-X, follow the software's instructions to e-file the amendment.
To see how to amend your taxes, click here:
Steps to amend in TurboTax
How to file amendment
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