If my wife put our child's SSN on her return but did not claim her as a dependent, how come it will not allow me to file my return with the same SSN as dependent?

[PatriciaR · Accepted solution]

To prevent fraudulent returns, the IRS will only accept each dependent's SSN once in their e-file system. Because the other parent filed first and used your child’s SSN, no further e-files using that SSN will be accepted. 

 You will need to print, sign, and mail your tax return to the IRS.  Your tax return will be accepted if you paper file.