Unfortunately you cannot add an attachment to an e-filed tax return.
TurboTax doesn't provide this feature, in part because the IRS and state e-file systems would not be able to recognize them as a tax form and check their accuracy.
Depending on what you are attaching, you may be able to efile and send the attachment separately using Form 8453.
Use Form 8453 to send any required paper forms or supporting documentation listed next to the checkboxes on Form 8453 (don’t send Form(s) W-2, W-2G, or 1099-R).
Don’t attach any form or document that isn’t shown on Form 8453 next to the checkboxes. If you are required to mail in any documentation not listed on Form 8453, you can’t file the tax
return electronically.
Your other choice is to print and file the return by mail, including the attachment and a letter/note explaining why you are sending it.
