An IRSN, or Internal Revenue Service Number, is a temporary identification number assigned by the IRS when a tax return is submitted without a valid Social Security number (SSN) or Individual Taxpayer Identification Number (ITIN). The IRS uses this number to identify and track the tax return within its system while the return is being reviewed or processed.
Please note that an IRSN is not a valid taxpayer identification number and cannot be used to file a tax return. Its purpose is limited to temporarily registering and tracking a return in the IRS system for administrative and processing purposes. To ensure that your tax return can be properly processed and accepted, you must provide a valid taxpayer identification number, such as an SSN or ITIN. If you do not have one, you may need to apply for an ITIN or otherwise resolve the missing identification information with the IRS.