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. 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. Are you planning an IRS business name change? You may not need a new EIN. In order to change your LLC name with the IRS, you'll need to mail them a letter and show proof of the state approving your LLC name change.