More and more tax returns are being rejected for electronic filing because another tax return has been submitted for the same social security number.
High net worth individuals are targets for criminals trying to get access to their withholdings and refunds.
By requesting an identity protection PIN from the IRS, criminals can’t file a tax return fraudulently on your behalf to try to steal your refund.
https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin
Be sure to get an IP PIN every year, it will make your tax filing process smoother. If another tax return has been submitted fraudulently on your behalf, you have to include an extra form in your tax return about being a victim of identity theft, and you have to paper file your return, which takes your valuable time to prepare the paper filing, and the processing is much slower than electronic filing.