Texas Tax Code - TAX § 183.0421. Tax Return Due Date

(a) A permittee shall file a tax return with the comptroller not later than the 20th day of each month.

(b) The return under this section must be in a form prescribed by the comptroller and must include a statement of the total sales and total taxable sales during the preceding month and any other information required by the comptroller.

(c) A tax due for a business day that falls in two different months is allocated to the month in which the business day begins.