Tex. Tax Code § 33.11

(a) In order to defray costs of collection, the governing body of a taxing unit or appraisal district in the manner required by law for official action may provide that taxes imposed on tangible personal property that become delinquent on or after February 1 of a year incur an additional penalty on a date that occurs before July 1 of the year in which the taxes become delinquent if:

(1) the taxing unit or appraisal district or another unit that collects taxes for the unit has contracted with an attorney under Section 6.30; and

(2) the taxes on the personal property become subject to the attorney's contract before July 1 of the year in which the taxes become delinquent.

(b) A penalty imposed under Subsection (a) is incurred by the delinquent taxes on the later of:

(1) the date those taxes become subject to the attorney's contract; or

(2) 60 days after the date the taxes become delinquent.

(c) The amount of the penalty may not exceed the amount of the compensation specified in the contract with the attorney to be paid in connection with the collection of the delinquent taxes.

(d) A tax lien attaches to the property on which the tax is imposed to secure payment of the penalty.

(e) If a penalty is provided under this section, a taxing unit or appraisal district may not:

(1) recover attorney's fees in a suit to collect delinquent taxes subject to the penalty; or

(2) impose an additional penalty under Section 33.07 on a delinquent personal property tax.

(f) If the governing body of a taxing unit or appraisal district provides for a penalty under this section, the collector for the taxing unit or appraisal district shall send a notice of the penalty to the property owner. The notice shall state the date on which the penalty is incurred, and the tax collector shall deliver the notice at least 30 and not more than 60 days before that date. If the amount of personal property tax, penalty and interest owed to all taxing units for which the tax collector collects exceeds $10,000 on a single account identified by a unique property identification number, the notice regarding that account must be delivered by certified mail, return receipt requested. All other notices under this section may be delivered by regular first-class mail.

(g) The authority granted to taxing units and appraisal districts under this section is to be construed as an alternative, with regards to delinquent personal property taxes, to the authority given by Section 33.07.