Kernrechtsfrage
Whether the taxpayer proved that all telephone and internet expenses were commercially justified and fully deductible under Art. 27 LIFD.
Extrahierter Entscheid
He did not prove full business necessity; only 3/5 of the claimed expenses were deductible.
Extrahierte Begründung
Under Art. 27 LIFD the taxpayer bears the burden of proving deductible business expenses. Monthly global bills and incomplete supporting documents did not exclude private use, especially since he worked from his private apartment and had not preserved detailed call records.