The costs of a cell phone may be a business expense, but only the additional costs in using a cell phone for business are deductible. The Tax Court has several interesting cases on this. In one case, the taxpayer paid a flat rate on a phone used for business and personal calls. The court held that as he paid a flat rate for his personal phone and incurred no additional charges for business use, he has no deduction. (Ritchie, TC Summary Opinion 2005-181).
Example from Ritchie: "Petitioner’s cell phone was a personal phone that he also used for business calls. Petitioner testified that he paid a flat rate, regardless of phone usage. Therefore, aside from the personal expense of the phone, which is rendered nondeductible under § 262, he incurred no additional charge for business use."
