(a) A person disputing the validity of a form, application, or other document filed with the retirement system has the burden of proving the document to be false, fraudulent, or otherwise invalid.
(b) A person seeking a correction based on an error caused by an act or omission of the retirement system or a subdivision has the burden of proving the error and the act or omission causing the error.
(c) A person described by Subsection (a) or (b) has the burden of showing:
(1) reasonableness and diligence in discovering the invalidity or error; and
(2) timeliness in notifying the retirement system or the appropriate subdivision.