Questão jurídica principal
Whether the federal appeal was admissible despite the prior final Zug assessment
Decisão extraída
The appeal was admissible; the cantonal instance chain had been exhausted in at least one canton and the final Zug assessment could be challenged together with the Aargau judgment.
Fundamentação extraída
In intercantonal tax disputes, Art. 100(5) BGG allows the final assessment from another canton to be included in the challenge.