Sole Proprietorship. Write to us at the address where you filed your return, informing the Internal Revenue Service (IRS) of the name change.Learn how to change your business name with the IRS. How do I fill this out? To fill out this form, you need to provide the old and new company names, your federal identification number, and contact details. You don't have to mail a special letter to the IRS to change your LLC name. If you've changed your legal or business name, you might need to notify the IRS or the Social Security Administration (SSA). The cost per unit for the goods described in the noncost information. Cal. Super. - 6th Dist. Who filled out and completed the application form?