Questão jurídica principal
Whether the appeal was admissible against the cantonal final judgment and to what extent earlier tax decisions could be challenged.
Decisão extraída
The appeal was admissible against the final cantonal judgment; the earlier lower-instance decisions could not be directly attacked.
Fundamentação extraída
The challenged act was the final judgment of the Aargau Administrative Court. In inter-cantonal double-taxation cases, a prior assessment from another canton may in principle also be attacked, but that did not matter here.