If you are the victim of identity theft or the IRS has issued you a CP01A Notice containing a six digit Identity Protection PIN, you will need to enter the number into the return to assist the IRS in processing the return.
Each member of your household that is included on your return has an entry line in the return. However, that does not mean all members of the household are required to have an IP PIN. Only enter the six digit number for the household member that received the IP PIN. Leave all other entries blank.
If you lost your PIN, visit the IRS website to have the PIN re-issued to you.