If someone file my taxes what should i do

[xmasbaby0]

Did that actually happen?   If someone uses your SSN on a tax return then what you can do is file your own tax return by mail, since your e-file will be rejected.   The IRS will process your mailed return and then they will sort out the duplicate use of your SSN.

Another thing you can do to prevent anyone from filing using your SSN is get an IRS IP PIN.

6-digit IP NUMBER FROM IRS

https://content.govdelivery.com/accounts/USIRS/bulletins/2af48f0?reqfrom=share

https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin

to get your new PIN from the IRS

- https://www.irs.gov/identity-theft-fraud-scams/retrieve-your-ip-pin

https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin

https://ttlc.intuit.com/questions/1900655-what-to-do-if-you-suspect-tax-related-identity-theft

Most important Follow the IRS procedures for reporting a fraudulent return, documented here: www.irs.gov/uac/Taxpayer-Guide-to-Identity-Theft

IRS INFORMATION REFERRAL TO REPORT VIOLATION OF TAX LAW

https://www.irs.gov/pub/irs-pdf/f3949a.pdf

If your Social Security number is compromised and you know or suspect you are a victim of tax-related identity theft, take these additional steps:

• Respond immediately to any IRS notice; call the number provided.
• Complete IRS Form 14039, Identity Theft Affidavit. Then print and mail or fax according to the instructions. 
• Continue to pay your taxes and file your tax return, even if you must do so by paper.

[MonikaK1]

It depends on exactly what happened.

If you tried to e-file your return and were notified that a return had already been filed with your Social Security number:

If your Social Security number is compromised and you know or suspect you are a victim of tax-related identity theft, the IRS recommends these actions:

• Respond immediately to any IRS notice: Call the number provided.
• If your e-filed return is rejected because of a duplicate filing under your Social Security number, or if the IRS instructs you to do so, complete IRS Form 14039, Identity Theft Affidavit. Use a fillable form at IRS.gov, print, then attach the form to your return and mail your return according to instructions.
• Visit IdentityTheft.gov for steps you should take right away to protect yourself and your financial accounts.

See Identity Theft Victim Assistance: How It Works for more information about how the IRS can help you.

If you believe your tax information may have been compromised, and you don't already have an Identity Protection PIN, the IRS recommends you use the Get An IP PIN tool in order to protect your tax account from tax related identity theft. The IP PIN authenticates you as the valid filer of the return. 

See this TurboTax help article for information about using an IP PIN to file your return.

If you previously contacted the IRS and did not have a resolution, contact them for specialized assistance at 800-908-4490. They have teams standing by to help you.

See this TurboTax tips article for more information about data security, phishing scams, and how to detect them.

You can also file your return by mail, but take the steps mentioned above to protect your identity. See this IRS webpage for additional steps you can take.

@deryne96