Tex. Civil Practice and Remedies Code § 18.091

(a) Notwithstanding any other law, if any claimant seeks recovery for loss of earnings, loss of earning capacity, loss of contributions of a pecuniary value, or loss of inheritance, evidence to prove the loss must be presented in the form of a net loss after reduction for income tax payments or unpaid tax liability pursuant to any federal income tax law.

(b) If any claimant seeks recovery for loss of earnings, loss of earning capacity, loss of contributions of a pecuniary value, or loss of inheritance, the court shall instruct the jury as to whether any recovery for compensatory damages sought by the claimant is subject to federal or state income taxes.