Question juridique clé
Whether the taxpayers had a duty under Art. 126 DBG to produce the requested bank statements.
Solution extraite
Yes. The requested bank statements could clarify the origin of disputed transfers and were relevant to the taxpayers' own assessment; the request was also proportionate and not unduly burdensome.
Motifs extraits
Art. 126 DBG preserves the established scope of the former Art. 89 BdBSt: taxpayers must provide documents that are suitable to establish tax-relevant facts, even if the authority is not strictly unable to assess without them. The request related to the taxpayers themselves, not third parties, and the effort required was reasonable.