I got reject code R0000-507-01so which one of my dependents was already claimed

[Anonymous]

you can try calling IRS 800-829-1040 select option 2. 

no one at TT would know and the reject code doesn't say.   

if you are entitled to all the dependents on your return,  you'll have to paper file.  

Eventually the IRS will send both of you a notice asking you to amend.  If no one does, the IRS will send another notice asking each of you to provide proof.   The one with the better proof gets it and the other gets a tax bill.  

[Sjadehussey]

Would you still get your return if you're the one who had to mail out your return?