Question juridique clé
Whether the taxpayer proved that all telephone and internet expenses were commercially justified and fully deductible under Art. 27 LIFD.
Solution extraite
He did not prove full business necessity; only 3/5 of the claimed expenses were deductible.
Motifs extraits
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.