Tex. Tax Code § 151.0595

(a) In this section, "remote seller" means a seller whose only activities in this state are described by Section 151.107(a)(4) or (5).

(b) A remote seller required to collect and remit one or more local use taxes in connection with a sale of a taxable item made by the remote seller shall compute the amount to collect and remit using:

(1) the combined rate of all applicable local use taxes authorized or governed by Title 3; or

(2) at the remote seller's election, the single local use tax rate published in the Texas Register as required by Subsection (d).

(c) A remote seller who elects under Subsection (b)(2) to use the single local use tax rate shall notify the comptroller of the election before using that rate. The election applies to all sales of taxable items made by the remote seller unless the remote seller revokes the election by notifying the comptroller. Notice to the comptroller under this subsection must be in the form and manner provided by the comptroller.

(d) The single local use tax rate effective in a calendar year is equal to the estimated average rate of local sales and use taxes imposed in this state during the preceding state fiscal year, as determined under Subsection (e). Before the beginning of a calendar year, the comptroller shall publish in the Texas Register notice of the single local use tax rate that will be in effect for that calendar year.

(e) As soon as practicable after the end of a state fiscal year, the comptroller shall determine the estimated average rate of local sales and use taxes imposed in this state during the preceding state fiscal year by:

(1) dividing the total amount of net local sales and use taxes remitted to the comptroller under this section and Title 3 during that state fiscal year by the total amount of net state sales and use taxes remitted to the comptroller under this chapter during that state fiscal year;

(2) multiplying the amount computed under Subdivision (1) by the rate provided by Section 151.051; and

(3) rounding the amount computed under Subdivision (2) to the nearest .0025.

(f) Notwithstanding Section 111.104(b), a purchaser may annually apply for a refund of any amount by which the amount of use tax computed using the rate described by Subsection (b)(2) and paid by the purchaser exceeds the amount the purchaser would have paid if that tax had been computed using the rate described by Subsection (b)(1). The comptroller may adopt rules regarding the procedure and proof required for the refund.

(g) A person storing, using, or consuming in this state a taxable item purchased from a remote seller is not liable for any additional amount of local use tax authorized or governed by Title 3 if the remote seller elects under Subsection (b)(2) to use the single local use tax rate and the person pays to the remote seller the amount of local use tax computed on the purchase using the single local use tax rate.

(h) The comptroller shall administer, collect, and enforce local use taxes computed using the single local use tax rate.

(i) The comptroller shall apportion and distribute revenue from local use taxes computed using the single local use tax rate as provided by Section 403.107, Government Code.

(j) The comptroller may adopt rules to administer this section.