...
Rule Text: Submission must not be a duplicate of a previously accepted submission.
In order to To correct the error, reference the DataValue (this indicates what person or number the rejection is related to). For more information, regarding how to view the details and data values related to rejections and refusals reference Viewing Reject and Refusals.
...
Possible Causes:
The taxpayer's information is entered incorrectly and the IRS system thinks it is a different person (double-check the SSN, name, and birthday).
The taxpayer has filed elsewhere.
The taxpayer received a quote somewhere else, and they filed the return without their consent.
The taxpayer has been a victim of identity theft.
The return has been Queued and Transmitted more than once.
Possible Resolutions:
...
Cause 1: The tax return has been submitted more than one time by your office.
Resolution: Contact CTTS to complete a Status Sync at 618-252-6505.
...
Possible Cause 2: The taxpayer's return was filed elsewhere without their consent.
This could be due to error or identity theft.
Resolution: If the taxpayer would still like to file with you and believes this is an error, collect payment upfront and paper file the return along with Form 14039.
...
Possible Cause 3: The taxpayer filed elsewhere willingly.
Resolution: If you issued advance money, try to recoup those funds.
...
Possible Cause 4: The taxpayer's information is entered incorrectly
...
If the taxpayer has not filed anywhere else, and believes they are a victim of identity theft, paper file and complete Form 14039.
...
and the IRS system thinks it is a different person (double-check the SSN, name, and birthday).
Resolution: Correct the taxpayer’s information, resign, and resubmit.
...