Why am I getting an efile transmission failure error because a return with the same SSN or EIN has previously been submitted?

[furlongcpa-outlo]

See the question.  Has someone filed a fraudulent return for my client or could it be something else?  

[sjrcpa]

Could be a fraudulent return was filed, or it could be a return was filed by mistake.

[johnsmith1]

At Ledger Labs, we see this error when the IRS system has already accepted a return with the same SSN or EIN for that tax period. Only one return per taxpayer can be transmitted. We can help you verify if a duplicate submission or pending amendment exists and guide you on the next steps.