One of our 4 social security numbers was already used to file a return but we do not know which of the four

[mhumphrey]

No!  That is not a good answer.  TurboTax was compromised.  I was told by one of your fellow employees that MY social security number was used to create a brand new account with a brand new email to file a return in MY name!  TurboTax allowed this to happen!  I have been a customer of TurboTax since 2006  I need someone to call me again ASAP before I contact an attorney.  I am going to file a police report today but I need a call back.  I have already called and have been waiting for a call back.  This is YOUR fault and YOUR problem that allowed some scumbag to file.  I have had the same email for 18 years and all TurboTax did was send an email that looked suspicious.  I forwarded that email the day I received it to the IRS.  Call me now!

[Hal_Al]

Again, this is a user to user to user forum. You will get no help from TT by posting here

[Hal_Al · Accepted solution]

If someone else claimed you, or your dependent,  inappropriately, and if they file first, your return will be rejected if e-filed. You would then need to file a return on paper, claiming yourself, if appropriate. The IRS will process your return and send you your refund, in the normal time. Shortly (up to a year) thereafter, you’ll receive a letter from the IRS, stating that your dependency was claimed on another return. It will tell you that if you made a mistake to file an amended return and if you didn't make a mistake to do nothing. The other party will get the same letter you did. If one of you doesn't file an amended return, unclaiming the dependency, the next letter, from the IRS, will require you to provide proof. Be sure to reply in a timely manner.

Winner gets the tax benefits; loser gets to pay the IRS back with penalties and interest.

The usual suspects are:

1. The parent the child lives with.
2. The other parent. 
3. The child claimed his own exemption.
4. Some other member of the household (e.g. grandparent)
5. Someone else the child lived with for part of the year

[mhumphrey]

I found out from TurboTax that someone was able to hack in and create a all new return and start a new account in my name with the only notice I received was a suspicious looking email from TurboTax.  No other attempt to get up with me but through email.  They dropped the ball on this one, I want my full Federal and Stare refunds fronted to me until this is resolved.  They were able to open an new account with all of my information along with my wife's and two dependents.  TurboTax, you dropped it big time!  A compromise in security that could haunt me and my family for years to come

[Hal_Al]

This is only a user to user forum.
To contact TurboTax (TT) support:
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