On August 19, the IRS Chief Counsel released an advice memorandum stating that certain methods for mixing taxable fuel to feedstock for, or derived from, anaerobic digestion processes cannot receive the alternative fuel mixture tax credit, since it is not used in actual energy production. The credit is only available for fuel mixtures qualified under Section 6462(d)(2), even if the amount added is as small as 0.1%. Those fuels must actually be sold for use as fuel and would not apply to a mixture used in anaerobic digestion. On the issue of substrate, the memorandum left it to case-by-case agency discretion, but it did explicitly say that unblended substrate used in anaerobic digestion did not qualify.