The increasing use of compostable plastics highlights the need for a detailed evaluation of their biodegradation behaviour under controlled end-of-life treatment conditions. In this study, the biodegradation of a commercial poly (butylene adipate-co-terephthalate)/thermoplastic starch (PBAT/TPS) blend used for bioplastic bag production was investigated under laboratory-scale composting conditions. Standard aerobic composting test conducted according to ISO 14855-1 was compared with an experimental approach combining anaerobic digestion and subsequent composting at modified conditions. Biodegradation was assessed through cumulative CO₂ evolution, moreover, a disintegration analysis, kinetic modelling, microplastic quantification and phytotoxicity testing was carried out on the samples. PBAT/TPS samples reached a final biodegradation of 54.88 ± 4.37 % after 90 days at standard conditions.