(a) In this section, “contribution defendant” means any defendant, counterdefendant, or third-party defendant from whom any party seeks contribution with respect to any portion of damages for which that party may be liable, but from whom the claimant seeks no relief at the time of submission.
(b) Each liable defendant is entitled to contribution from each person who is not a settling person and who is liable to the claimant for a percentage of responsibility but from whom the claimant seeks no relief at the time of submission. A party may assert this contribution right against any such person as a contribution defendant in the claimant’s action.

(c) The trier of fact shall determine as a separate issue or finding of fact the percentage of responsibility with respect to each contribution defendant and these findings shall be solely for purposes of this section and Section 33.015 and not as a part of the percentages of responsibility determined under Section 33.003. Only the percentage of responsibility of each defendant and contribution defendant shall be included in this determination.
(d) As among liable defendants, including each defendant who is jointly and severally liable under Section 33.013, each contribution defendant’s percentage of responsibility is to be included for all purposes of Section 33.015. The amount to be contributed by each contribution defendant pursuant to Section 33.015 shall be in proportion to his respective percentage of responsibility relative to the sum of percentages of responsibility of all liable defendants and liable contribution defendants.