Texas Civil Practice and Remedies Code - CIV PRAC & REM § 16.069. Counterclaim or Cross Claim

(a) If a counterclaim or cross claim arises out of the same transaction or occurrence that is the basis of an action, a party to the action may file the counterclaim or cross claim even though as a separate action it would be barred by limitation on the date the party's answer is required.

(b) The counterclaim or cross claim must be filed not later than the 30th day after the date on which the party's answer is required.