The LCFS further differs from both the RFS and CFR by allowing fuel producers to input site-specific (or "pathway-specific") values for some LCA parameters related to the feedstock production stage (e.g., fertilizers; Table ). Calculations to determine the CI of fuels produced for LCFS compliance must be performed in simplified calculators or using CA-GREET. However, these models rely on non-site-specific assumptions for other key factors related to feedstock production (e.g., emissions of greenhouse gases such as N2O from fertilized cropland). The LCFS may allow for further adjustment of feedstock production CIs to include site-specific biogeochemistry (e.g., Table transportation fuels by offsetting qualifying taxpayers' federal tax liability. Taxpayers interested in claiming this credit must prove to the U.S. Internal Revenue Service that they produced or sold transportation fuels with lower greenhouse gas emissions than conventional fossil-based fuels. In the case of SAF, the credit is worth 0.09 $×L -1 or 0.46 $×L -1 , depending on whether the fuel is produced according to certain wage and apprenticeship requirements, multiplied by a factor that compares the SAF CI to a baseline fuel CI (see for additional details).