Sec. 13.5. A personal representative, including an executor, an administrator, a successor personal representative, a special administrator, or a person performing substantially the same function with respect to a decedent's estate, is a fiduciary for purposes of this chapter if:
(1) under the terms of a decedent's will this chapter applies to the administration of the estate; or
(2) under other applicable law, the personal representative is required or allowed to account for and distribute income received during administration of the estate separately from the corpus of the estate.