Is a Guardianship a Separate Entity for Income Tax Purposes?

A guardianship in many ways appears to be an entity.  The term "guardianship" itself connotes a separateness from the ward (the person who is subject to the guardianship).   In other ways, a guardian acts merely as a fiduciary and on behalf of, and not separate to, the ward.  Thus, a question arises as to whether a guardianship is a separate entity from its ward for federal income tax purposes.  Estates, trusts, corporations, and partnerships must file income tax returns separate from those returns filed by their respective beneficiaries, shareholders, and partners.  Should a guardianship file its return separate from that of the ward?  The answer is that unlike estates, trusts, corporations, and partnerships, a guardianship is not treated as a separate entity from the ward.  Treas. Reg. § 1.641(b)-2.  The guardian files the ward's income tax return (but does so on behalf of the ward).  In addition, the ward's social security number is used for tax purposes.