If you are filing a current year Form 1065, mark the appropriate name change box on the form: Page 1, Line G, Box 3. 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.The namechange letter should clearly state that your business name has changed. The first step is to file a form called the Certificate of Amendment with the Secretary of State and wait for it to be approved. 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. 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. You have to mail your business name change request to the mailing address in which you would have to send your tax return. Use Form 8822-B to notify the Internal. Corporation Engaged in a U.S. Trade or Business complete lines 1–18 (as applicable).