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. Business name change. If you've changed your legal or business name, you might need to notify the IRS or the Social Security Administration (SSA). 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. Name Change Information - helpful brochure with information about obtaining a name change for you, or your minor child, and sample forms. Are you planning an IRS business name change?