(a) This section applies to civil actions only, but not to an action on a sworn account.
(b) Unless a controverting affidavit is served as provided by this section, an affidavit that the amount a person charged for a service was reasonable at the time and place that the service was provided and that the service was necessary is sufficient evidence to support a finding of fact by judge or jury that the amount charged was reasonable or that the service was necessary. The affidavit is not evidence of and does not support a finding of the causation element of the cause of action that is the basis for the civil action.

(c) The affidavit must:
(1) be taken before an officer with authority to administer oaths;
(2) be made by:
(A) the person who provided the service; or
(B) the person in charge of records showing the service provided and charge made; and
(3) include an itemized statement of the service and charge.
(d) The party offering the affidavit in evidence or the party’s attorney must serve a copy of the affidavit on each other party to the case by the earlier of:
(1) 90 days after the date the defendant files an answer;
(2) the date the offering party must designate any expert witness under a court order; or
(3) the date the offering party must designate any expert witness as required by the Texas Rules of Civil Procedure.
(d-1) Notwithstanding Subsection (d), if services are provided for the first time by a provider after the date the defendant files an answer, the party offering the affidavit in evidence or the party’s attorney must serve a copy of the affidavit for services provided by that provider on each other party to the case by the earlier of:
(1) the date the offering party must designate any expert witness under a court order; or
(2) the date the offering party must designate any expert witness as required by the Texas Rules of Civil Procedure.
(d-2) The party offering the affidavit in evidence or the party’s attorney must file notice with the clerk of the court when serving the affidavit that the party or the attorney served a copy of the affidavit in accordance with this section. Except as provided by the Texas Rules of Evidence, the affidavit is not required to be filed with the clerk of the court before the trial commences.
(e) A party intending to controvert a claim reflected by the affidavit must serve a copy of the counteraffidavit on each other party or the party’s attorney of record by the earlier of:
(1) 120 days after the date the defendant files its answer;
(2) the date the party offering the counteraffidavit must designate expert witnesses under a court order; or
(3) the date the party offering the counteraffidavit must designate any expert witness as required by the Texas Rules of Civil Procedure.
(e-1) Notwithstanding Subsection (e), if the party offering the affidavit in evidence serves a copy of the affidavit under Subsection (d-1), the party offering the counteraffidavit in evidence or the party’s attorney must serve a copy of the counteraffidavit on each other party to the case by the later of:
(1) 30 days after service of the affidavit on the party offering the counteraffidavit in evidence;
(2) the date the party offering the counteraffidavit must designate any expert witness under a court order; or
(3) the date the party offering the counteraffidavit in evidence must designate any expert witness as required by the Texas Rules of Civil Procedure.
(f) The counteraffidavit must give reasonable notice of the basis on which the party serving it intends at trial to controvert the claim reflected by the initial affidavit and must be taken before a person authorized to administer oaths. The counteraffidavit must be made by a person who is qualified, by knowledge, skill, experience, training, education, or other expertise, to testify in contravention of all or part of any of the matters contained in the initial affidavit. The counteraffidavit may not be used to controvert the causation element of the cause of action that is the basis for the civil action.
(g) The party offering the counteraffidavit in evidence or the party’s attorney must file written notice with the clerk of the court when serving the counteraffidavit that the party or attorney served a copy of the counteraffidavit in accordance with this section.
(h) If continuing services are provided after a relevant deadline under this section:
(1) a party may supplement an affidavit served by the party under Subsection (d) or (d-1) on or before the 60th day before the date the trial commences; and
(2) a party that served a counteraffidavit under Subsection (e) or (e-1) may supplement the counteraffidavit on or before the 30th day before the date the trial commences.
(i) Notwithstanding Subsections (d), (d-1), (d-2), (e), (e-1), (g), and (h), a deadline under this section may be altered by all parties to an action by agreement or with leave of the court.