How do I file Federal return by mail for my deceased brother?

[IreneS]

I'm sorry for your loss.

Print out the return and sign your own name.  Write "Personal Representative" next to your signature.

When filing a return on behalf of a deceased person, unless you are the spouse, you must file additional documents:

• If you’re the court-appointed executor, attach a copy of the court document that authorizes you to act. This may be called your “Letters Testamentary,” or something similar, depending on the state.
• If a court hasn’t appointed you to represent the estate, file IRS Form 1310, Statement of Person Claiming Refund Due a Deceased Taxpayer, with the return.

For additional information, please see IRS Pub. 559 - Survivors, Executors, and Administrators