SECTION 5. INFORMATION ABOUT

OTHER FUEL REGISTRATIONS

Section 4101(a)(1) requires that every person required to be registered with respect to the tax imposed by § 4041(a) or 4081, every person producing or importing biodiesel (as defined in § 40A(d)(1) including agri-biodiesel and renewable diesel) or alcohol (as defined in § 6426(b) (4)(A)), every person producing or importing sustainable aviation fuel (as defined

in § 40B), and every person producing second generation biofuel (as defined in § 40(b)(6)(E)), register under § 4101.

Section 4081(a)(1) imposes an excise tax on certain removals, entries, and sales of taxable fuel. Section 4083(a) defines taxable fuel as gasoline, diesel fuel, and kerosene. Section 4041(a) imposes an excise tax on certain sales and uses of diesel fuel and kerosene.

Depending on the type of transportation fuel being produced and sold, a person producing fuel eligible for the § 45Z credit may have additional registration obligations under § 4101 and § 48.4101-1 and thus may be required to be registered under other activity letters (in addition to Activity Letters “CN” and/or “CA”), including the following:

(A) Activity Letter “SA” (producers or importers of sustainable aviation fuel as defined in § 40B);

(B) Activity Letter “S” (enterer, position holder, refiner, terminal operator, or throughputter of gasoline, diesel fuel (including a diesel-water fuel emulsion), or kerosene, or industrial user of gasoline);

(C) Activity Letter “M” (blenders of gasoline, diesel fuel (including a diesel-water fuel emulsion) or kerosene, producing a taxable fuel outside the bulk transfer/terminal system, including blenders of alcohol fuel mixtures, alternative fuel mixtures, biodiesel mixtures, and renewable diesel mixtures);

(D) Activity Letter “AB” (producers and importers of agri-biodiesel);

(E) Activity Letter “AF” (producers and importers of alcohol);

(F) Activity Letter “NB” (producers and importers of biodiesel (other than agri-biodiesel) and renewable diesel); and

(G) Activity Letter “SB” (producers of second generation biofuel).

If a person is producing SAF eligible for the § 45Z credit and that SAF also meets the definition of sustainable aviation fuel under § 40B, such person must also be registered under Activity Letter “SA”. ⁶

For additional guidance for fuel registrations, see Notice 2023-6 (guidance on sustainable aviation fuel credits under §§ 40B and 6426(k)), Notice 2008-110, 2008-51 I.R.B. 1298 (guidance on biodiesel and registration for the cellulosic biofuel producer credit), ⁷ and Notice 2005-4, 2005-2 I.R.B. 289 (guidance on alcohol and biodiesel fuel tax credits and payments), as modified by Notice 200562, 2005-35 I.R.B. 443 (guidance for certain biodiesel issues not addressed in Notice 2005-4).