Sec. 4. (a) This section applies to suits or proceedings:
(1) in which an executor or administrator is a party;
(2) involving matters that occurred during the lifetime of the decedent; and
(3) where a judgment or allowance may be made or rendered for or against the estate represented by the executor or administrator.
(b) This section does not apply in a proceeding to contest the validity of a will or a proceeding to contest the validity of a trust.
(c) This section does not apply to a custodian or other qualified witness to the extent the witness seeks to introduce evidence that is otherwise admissible under Indiana Rule of Evidence 803(6).
(d) Except as provided in subsection (e), a person:
(1) who is a necessary party to the issue or record; and
(2) whose interest is adverse to the estate;
is not a competent witness as to matters against the estate.
(e) In cases where:
(1) a deposition of the decedent was taken; or
(2) the decedent has previously testified as to the matter;
and the decedent's testimony or deposition can be used as evidence for the executor or administrator, the adverse party is a competent witness as to any matters embraced in the deposition or testimony.