Retirement plan trustees shouldn't use the plan sponsor's EIN for their retirement plan trust. IRA trustees/custodians should not use the IRA owner's social security number for the IRA to report unrelated business taxable income on Form 990-T. See the EIN application page for further information. To obtain an EIN for a retirement trust or for an Individual Retirement Account (IRA) trust, the plan trustee or practitioner can either apply online, or mail or fax Form SS-4, Application for Employer Identification Number to the IRS. Apply online IRS issues the EIN immediately once the information on the application is validated. At "What type of legal structure is applying for an EIN," check "View Additional types, including Tax-Exempt and Governmental Organizations" and click "Continue." On the "Additional Types" page, select "Employee Plan (401(k), Money Purchase Plan, etc). Do not select "Other Non-profit/Tax Exempt Organization" because this will generate an EIN for a tax-exempt organization, such as a 501(c)(3) organization. If you applied for an EIN for a retirement trust by selecting "Other Non-profit/Tax Exempt Organization" and received a CP 575E Notice, you may contact Employee Plans Customer Account Services for help. For paper Form SS-4 applications only, check "Other" on Line 9a and indicate that the EIN is for a retirement trust. Deactivated EINs If your retirement trust EIN has been deactivated, you can re-establish the EIN by sending a fax request (855-214-7520) to the EP Entity Control Unit in Ogden, Utah, and include the: EIN in question trust name sponsor's or trustee's mailing address name, address and telephone number of the person who can answer additional questions Or you can mail the request to: USPS Address Internal Revenue Service Attn. EP Entity, M/S 6273 Ogden, UT 84201 Private Delivery Service Address Internal Revenue Service 1973 N Rulon White Blvd. Attn. EP Entity, M/S 6273 Ogden, UT 84404 A retirement plan trustee should apply for an EIN for the plan's trust in order to properly: report Form 945 for deposits and other income tax withholding information, provide Form W-9 to requesters of tax identification number certifications, report Form 990-T for exempt organization business income, and report retirement plan trust information An IRA trustee/custodian should apply for an EIN for the IRA to report unrelated business taxable income on Form 990-T.