Problem: The IRS rejected your Federal Tax Return - not eFile.com - because the Social Security Number you provided can not be the same as another qualifiying child on a previously accepted tax return this year. Did your spouse or previous spouse claim the same dependent?
Solution: Sign into your eFile.com account: https://mytaxes.efile.com/1040/SignIn/, click on Federal Taxes and Name & Address or Dependent and correct the SSN. If the SSN is correct and you wish to dispute the claim of the dependent please go "My Account" on eFile.com and Print, Download, Sign and Mail your tax return to the IRS and/or State. Then read this here to dispute the claim of the dependent:
If you can correct the SSN do that and continue with your re-eFile process. You can re-eFile your return at no additional charge.
Contact us with questions: https://www.efile.com/tax-service/contact/efile-contact/