In which cases can you not file an objection?
In general, it is not possible to lodge an objection against an 'ex officio reduction' of a tax assessment, because objection is only possible if the law stipulates that the decision must be taken in the form of a decision open to objection. This is not the case with an 'ex officio reduction'.
N.B. A notice of objection can be submitted against an 'ex officio assessment'. An ex officio assessment is if no tax return has been submitted and the inspector will estimate the assessment based on the documents available at BCN.