Tex. R. Civ. P. 658a
No writ of garnishment shall issue before final judgment until the party applying therefor has filed with the officer authorized to issue such writ a bond payable to the defendant in the amount fixed by the court's order, with sufficient surety or sureties as provided by statute, conditioned that the plaintiff will prosecute his suit to effect and pay to the extent of the penal amount of the bond all damages and costs as may be adjudged against him for wrongfully suing out such writ of garnishment.
After notice to the opposite party, either before or after the issuance of the writ, the defendant or plaintiff may file a motion to increase or reduce the amount of such bond, or to question the sufficiency of the sureties. Upon hearing, the court shall enter its order with respect to such bond and the sufficiency of the sureties.
Should it be determined from the garnishee's answer if such is not controverted that the garnishee is indebted to the defendant, or has in his hands effects belonging to the defendant, in an amount or value less than the amount of the debt claimed by the plaintiff, then after notice to the defendant the court in which such garnishment is pending upon hearing may reduce the required amount of such bond to double the sum of the garnishee's indebtedness to the defendant plus the value of the effects in his hands belonging to the defendant.
Tex. R. Civ. P. 658a