Tex. R. Civ. P. 507.1
As amended through August 27, 2024
A justice court loses plenary power over a case when an appeal is perfected or if no appeal is perfected, 21 days after the later of the date judgment is signed or the date a motion to set aside, motion to reinstate, or motion for new trial, if any, is denied.
Tex. R. Civ. P. 507.1