Changing your business’s name can be as simple as writing a letter to the Internal Revenue Service (IRS) or filling out a particular field in your usual tax return form—as long as your change does not include a change of ownership or address.
If the Employer Identification Number (EIN) was recently assigned and filing liability has yet to be determined, write to the IRS as IRS-Stop 343G, Cincinnati, OH 45999 and inform them of the change.
Otherwise, consult the table below from the IRS’s website to find your next steps:
Disclosure
Our comments may not contain a full description of all the facts or a complete exposition and analysis of all relevant authorities. Furthermore, the use of certain words such as “should, would, or will” is merely for grammatical convenience, is not intended to indicate a specific level of authority regarding a particular issue, and no explicit or implicit references should be taken there from. Our comments expressed herein are based upon the provisions of the Internal Revenue Code and Regulations in force on the date hereof, all proposed amendments to these Acts, Regulations and treaties publicly announced by the relevant authorities. Each and all of these authorities are subject to change at any time. Any such change could be given retroactive effect with respect to the transactions described herein and could cause the conclusions provided to become invalid, in whole or in part, with respect to any entity involved. There can be no assurance that these authorities will not disagree with, or challenge, the views set forth in this memorandum or that any such challenge will be unsuccessful.
Source: https://www.irs.gov/Individuals/Business-Name-Change