The Tax Court can apply the Cohan rule to allow a deduction for estimated expenses in some cases, but not for business driving. There is a specific Tax Code provision that overrides the Cohan rule when it comes to vehicle write-offs. That’s what one taxpayer found out when the Tax Court disallowed his deduction for car and truck expenses. His mileage logs were questionable, putting him in 2 states at the same time and making no distinction between nondeductible commuting and deductible business driving. #IdeaoftheDay