just looked at her tax return docs and notice a mistake... she did not check the box "Someone can claim you as a dependent"

What now? What is my recourse? Is there a way to correct her tar return?

@main0stage You will have to paper file if you wish to claim your daughter on your return. And your daughter will need to amend to indicate that someone can claim her. 

@main0stage Paper filing your return will be faster than waiting on your daughters return to be amended. Amended returns can take up to 16 weeks to process. Mailed returns take 6-8 weeks to process. If you extend, do pay any taxes due by 4/15/19 to the federal and state. 

IRS direct pay

Check with your state revenue site for direct payment options.

PaulaM thank you again. Let me rephrase my question. When my paper based tax-return reaches IRS, wouldn't they run into same issue of my daughter's return already in the records where she cannot be claimed as dependent? Could my paper-based tax return then rejected as well for same reason?

We have attempted to Claim our Son 2 years in a row with no success.   The reason - he makes more than 4K per year!  And of course this isn't the situation in your family I know.

But the reason why the IRS is most likely Rejecting your Return is because you Claimed your Daughter as a Dependant and she too Filed.   So they most likely want to compare the 2 Tax Filings to ascertain there isn't an overlapping of dependants.

Yes, and you may be able to do so on the Federal website.   Check it out.   As a Student the IRS is so very tolerant of much.

My Son was Full Time, but not younger.  My inability to Claim him was based on his income - as I was led to believe by the answer and subsequent response via the Turbo Tax response.  And believe me when I confirm that we did provide more than 1/2 his support.

Will not reject the on-line filing or the paper filing?   I have the exact same situation.  We have mailed a paper amended return for my son to correct the error.    Once his amended return is processed can I file electronically or should I print and mail my return now?   I am expecting a small refund.  

2nd question - COVID 19 stimulus payments.  If the IRS uses my son's status before the amendment is processed I suppose there is a chance he would get a $1200 check - which would be an error.  I also suppose there is a chance I will not get the $500 per child ( he is the only dependent left).  Any words of wisdom here?   Should I mail my paper return asap and hope the IRS enters that information before the stimulus payments?