My tax return was rejected because someone else "claimed" my son as a dependent; however, no one else claimed my son as a dependent.

[Rachel_W]

Unfortunately, if the IRS has in their system that someone claimed your son as a Dependent, you will not be able to E-File your return.  Instead, you will need to paper file your return.  

Once the IRS receives your return, they will send out paperwork to you and to the other person they are showing claimed your son in order to determine who should be claiming him.  Once you prove you are the rightful claimer, they will issue the refund to you and rescind it from the other person.  

Please check out the TurboTax FAQ below for instructions on how to paper file your return:

https://ttlc.intuit.com/replies/3401713