As far as I know most countries have clear, public algorithms for tax reports, may I ask which country you are talking about? In any case your problem is one o

As far as I know most countries have clear, public algorithms for tax reports, may I ask which country you are talking about? In any case your problem is one of an incompetent person not being able to explain the decision, not a black box algorithm (since the program you are talking about has been programmed, not taught like an AI). You have recourses (though probably difficult to exercise) unlike with a decision officially based on an AI in which case it is technically impossible to motivate the decision.