Sole Proprietorship. Write to us at the address where you filed your return, informing the Internal Revenue Service (IRS) of the name change.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. To update your legal name with DOR, you can send proof of your legal name change to DOR through the mail or an emessage. Usually, you should include the following details in the letter: Your EIN. The old name of the business as mentioned in the IRS records. Follow our stepbystep guide covering how to properly amend your business name, to stay compliant with all state and local laws. 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. An exempt organization that has changed its name generally must report the change on its next annual return (such as Form 990 or 990EZ).