What to do after you file your taxes in April and Afterwards, you receive a tax form in the mail from a financial institute that you needed to enter into your tax return? Aren't they supposed to get the forms to you by mid-February? Are they held accountable at all? Do I need to file an amended tax return?
If you omitted a tax document when you filed, you will need to amend your return. As for the financial institution sending the form to you after early February, have a conversation with them. Some financial institutions do not have everything ready very early in the tax season; it is your responsibility to be aware of the documents you need to file completely and accurately, even if it means waiting to file.
Wait until your original return has been fully processed before you amend, and make sure you have saved a pdf of the original return before you amend. (If you do not save it as a pdf, the amended return will overwrite the original, and the original will be lost forever)
Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.
You can watch for information here:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
Perhaps using a checklist of tax documents would help you to avoid filing without all of your information next time.
https://blog.turbotax.intuit.com/life/tax-documents-checklist-how-to-win-big-this-tax-season-53328/
Wait until your original return has been fully processed before you amend, and make sure you have saved a pdf of the original return before you amend. (If you do not save it as a pdf, the amended return will overwrite the original, and the original will be lost forever)