An IRS pin is a pin assigned to you by the IRS (it changes every year).
Only the person with the correct IRS pin can submit tax forms.
This way, no one who steals your identity can then submit false tax forms and claim a huge refund in your name.
Thanks for the information. With the reports of hundreds of tax refunds being sent by the IRS to the same addresses, I didn’t think the IRS was doing anything to correct the problem.