With the information provided I am not sure why you would be required to mail... but some of the most common reasons are listed below.

When you have to paper file a tax return

Although the IRS urges taxpayers to e-file whenever possible, there are also times when the service requires taxpayers to mail in a paper return and other tax forms.

1. You missed the e-filing deadline — and can’t wait

Typically, your federal income tax return is due on April 15 (or thereabouts) every year. You can usually get a filing extension to Oct. 15, although that’s not an extension of time in which to pay your taxes. Any tax you owe is still due Tax Day.

You can e-file a return at any time of year — except when the IRS shuts down its Modernized e-File system , or MeF, to prepare for the next year’s tax filing season. Last year, the shutdown deadline was Nov. 17.

If you absolutely can’t wait until the IRS begins accepting e-filed individual tax returns (usually in late January of the following year) again, you might have to file a paper return.

2. You need to file an amended return

There are many reasons why you might need to file an amended tax return, but there’s only one way to do it:  You’ll have to mail a paper Form 1040X to the IRS.

Even if you use an online tax preparation and filing service  to complete the 1040X, you’ll still need to print and mail it.

3. You’re seeking relief as an injured spouse

If your spouse owes certain kinds of debt — such as past-due taxes, state debts, unpaid student loans or late child support payments — and you file a joint federal tax return, the U.S. Department of the Treasury might be able to take some or all of your joint refund to pay that debt. Requesting injured spouse relief could help you keep the portion of your shared refund that is yours, while your spouse’s share goes toward paying their debts.

To apply for injured spouse relief you must complete and submit Form 8379. If you submit the form at the same time you file your joint return, you can e-file both together. However, if you already filed your federal return and it was accepted (for example, you discovered the IRS might take your refund after you filed), you’ll have to mail it.  And if you’re submitting it with an amended tax return, both must be filed on paper.

4. Your e-filed return keeps getting rejected

Returns can be rejected for many reasons. If it’s something minor, like a misspelled name or a missing form, you may be able to correct your return by resubmitting your e-filed return.

But you may have to file your return by mail if the IRS rejects your return for a bigger problem — such as someone else using your Social Security number or if someone on your return has already been claimed as a dependent on another already-processed return.

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5. Taxpayers who live or work outside the U.S.

If you are a U.S. citizen or resident alien who lives or works outside the United States, you will have to mail your return.

If you expect a refund or aren’t including a payment with the return, you can mail it to:

Department of the Treasury
Internal Revenue Service Center
Austin, TX 73301-0215

If you’re sending a payment, mail the return and your check or money order to:

Internal Revenue Service
P.O. Box 1303
Charlotte, NC 28201-1303

If I am mailing my tax returns, which forms go to the IRS? and which ones go to Department of Treasury?

Yes  You may click Federal Review in the Tax Home screen to check for errors.  If your income tax returns require a specific form/s not available for e-file, you may have to paper file your return.

When you print your income tax returns, it will specify which forms needed to be mailed , Taxpayers copy have a " Do not File" written across each pages. Vouchers will be printed as well.

none of the listed situations apply to me yet it keeps telling me I cannot file electronically. I lpaid for Turbo tax so I could file electronically, how do I fix it?

none of those situations apply to me yet TurboTax tells me I can't file my state return electronically because it's an amended return which it is not. How do get to chat with someone on here?

The fee is actually not for e-filing.  It is for our program to assist in creating your return.  Sometimes, unfortunately, you are not able to e-file.  Please see the Help Article here for more details. 

Try this and see if this clears the issue for you.  Please log completely out of TurboTax.  Then, in your browser, please clear your cache and delete your cookies.  After this, close completely out of the browser.  Re-open everything including logging back into TurboTax.  Also, you can try completing your return in a different browser as well.  

For further instructions on how to clear cache and delete cookies, please see the links below:

Clear Cache

Delete Cookies

If the above does not work, please reach out to us directly at the link here.  This will direct your inquiry to the correct department.