If you are a confirmed victim of identity theft and the IRS has resolved your related tax account issues, the IRS will mail you a CP01A Notice with an Identity Protection PIN (IP PIN) each year. You must include this IP PIN to file your tax returns (electronic or paper) for all future years. You will receive a unique IP PIN each year.
Starting in 2021, the IRS opened this up to allow you to voluntarily opt into the IP PIN program as a proactive way to protect yourself from tax-related identity theft. Below is a link with more information on the IP PIN program and on how to opt in.