If your morals allow you to not pay taxes then no bitcoin is not taxable, since its not traceable unless you put your information to the public and even then, the law can't persecute you since they cant be sure if that wallet might be yours or not. And that's in my opinion why most countries are hesitant about bitcoin knowing it would cause a tax evasion chaos.
I think we should draw the distinction between property taxes and income taxes. Bitcoin may be taxable as property but you should sell it for fiat to be taxable as income. And this is where you can easily get caught if you aim at tax evasion. They will see that your living standards don't match your official income, then they come after you and start asking questions. Not something that you would be eagerly looking for, especially in case of IRS.