I thought that I was done with my business taxes, so I put done...but I found additional expenses, license fees, and supplies that I didn't add, can i go back

If your e-filed return is pending, you will not be able to make any changes until it is accepted or rejected by the IRS. After that, you can amend your return. Please see How to amend (change or correct) a return you've already filed for more information.

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