Based on the CIs according to policies and spatially explicit LCA, the policy-induced CI differential for SAF produced from miscanthus is -137. ). The overestimated CI on behalf of the RFS is explained by the non-producer-specific fuel pathway SAF CI used by the program (Table ). The CFR overestimates and underestimates the CI similarly, but the use of a single program-based CI still cannot account for the potential variation in SAF CIs. The 45Z tax credit is the only policy that is likely to underestimate the SAF CI, because the CI is not producer-specific and estimates a higher amount of miscanthus-induced SOC storage (Table ). Regardless of over-or underestimation, the wide range of policy-induced CI differentials highlights the limitations of using a single fuel CI for program participation (for all four policies, but particularly for the RFS and LCFS). The variation in the SAF CI estimated via spatially explicit LCA (which corresponds to the variation in CI differential in Figure ) can be attributed to multiple spatially varying and uncertain parameters along the biofuel supply chain (e.g., miscanthus CI, biomass transport distance, biomass-to-biofuel conversion efficiency). Not ). Given that credit selling prices have been consistently greater than zero, the monetary undervaluation of SAF is directly linked to overestimated CIs on behalf of low carbon fuel policies (Figure ). These results suggest that the RFS will almost always undervalue SAF. While the CFR-induced price differential was estimated based on LCFS credit prices, these results indicate that the program is likely structured in a way that will undervalue SAF produced from miscanthus.