Rejected simply means that the government is saying that there are some errors in your return which needs to be fixed and is sending back your return.
If you e-filed your return and it comes back as rejected, you will not be able to electronically send it till the issue is fixed. If your return was rejected, you will receive an email from TurboTax letting you know and how to fix the issue. Sometimes returns get rejected if social security number or name doesn't match IRS records, or your last year's AGI (adjusted Gross Income) from your 2016 taxes doesn't match up.
Please see the TurboTax Faq below for more information on Rejected and how to fix a reject under Related Information:
https://ttlc.intuit.com/replies/4193396
