The IRS says a business expenses should be “ordinary and necessary” to be a legitimate tax deduction. Use that definition as a basic yardstick when determining if a cost is a valid business expense. Your CPA should be able to help you and it’s best to get advice before you make a decision, when she can help, rather than after. We instruct clients to turn in any expenses they are not sure about and let us make the call. If you don’t tell CPA about a bill you’ve paid because you don’t think it’s deductible, then I can guarantee that it won’t be deducted on your tax return!