You have to seperate transaction and withdrawal fees from tax that you may or may not declare every year to the government. In the latter case, even though Bitcoin isn't directly being mentioned as tax deductible in many countries, it doesn't mean you don't have to pay tax over everything you hold in Bitcoin. It adds up to your total wealth, plus the profits that you make are also subject to a general tax law. In short - Paying tax over your coins is a must. It's however up to you whether or not you declare everything honestly.