With the creation of the ICMS single-phase taxation regime for fuels, some guidelines have been published establishing procedures for the control, calculation, transfer, and deduction of the single-phase tax.   The following validation rules are related to single-phase taxation on fuels that were updated in the Technical Note NT2023.001 version 1.40 published on the NF-e Portal on 27 September 2023: – Rule N12-70: amended to provide for CST 02 (Own single-phase taxation on fuels) in exception 8, thus permitting the issuance of fuel NF-e to non-taxpayers; – Rules LA17-20, LA18-10, and LA18-20: changed to remove the exception condition that checks...