From December 2017 through January 2018, the IRS will send "IRS Notice CPO1A" letters to taxpayers who have contacted IRS and have been validated as being the victims of identity theft from a prior tax return. Both the letter and PIN will be auto generated based on the taxpayer's validated account information. The letter will contain a single use 6 digit PIN valid for this year only. Due to the process used in the development of the PIN, the Identity Theft PIN may begin with a zero.
If an individual loses their IP PIN, the original can be retrieved via the online IRS Get an Identity Protection PIN tool on the IRS website.