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. If you've changed your legal or business name, you might need to notify the IRS or the Social Security Administration (SSA). You don't have to mail a special letter to the IRS to change your LLC name. 1. How do I form a corporation? 2. How do I form a nonprofit corporation? An IRS LLC name change is perhaps the easiest one to perform.