m303I completed this course in 2016 and achieved a grade 2 pass. It's a very tough course, in my opinion. You should have completed M208 (or its equivalent) recently prior to starting M303 inModelo 303. IVA. Autoliquidación. Gestiones destacadas. Si desea confeccionar y presentar el modelo de forma electrónica. Modelo 303. Ejercicio 2025.