Learn how to change your business name with the IRS. If you are filing a current year Form 1065, mark the appropriate name change box on the form: Page 1, Line G, Box 3.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. 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. To complete the name change, submit the following documents to us: Change, replace or add an assumed name (doing business as) of a licensed business entity. The IRS asks that you send a letter, on company letterhead (if available) providing the name and Social Security Number of the owner(s) of the LLC. Type or print clearly. 1 Legal name of entity (or individual) for whom the EIN is being requested. If you've changed your legal or business name, you might need to notify the IRS or the Social Security Administration (SSA).