This Technical Report gives an overview of the suitability of <(hoch)14>C-based methods for the determination of the fraction of biomass carbon in solid recovered fuels, using detection by scintillation, gas ionization and mass spectrometry. The principle of the <(hoch)14>C method is to determine the biomass content by total carbon by measuring the amount of <(hoch)14>C present in the sample. The biomass content by total carbon of a material is calculated as the proportion of the isotope abundance of <(hoch)14>C in that material and the isotope abundance of <(hoch)14>C in the atmosphere at the time when the biomass was laid down.