It was reported a while ago that in Sweden 20 billion SEK are "lost" annually in the retail and restaurant industry due to black money. It's generally a good rule of thumb to do the opposite of what the IRS says. The state collecting (stealing) less money is a good thing. To escape being robbed is something we should encourage, right? Another thing you can do to reduce the tax revenues of the state is to always opt for takeaway. Then the VAT will be lower. And of course, never ask for a receipt.
It's tragic that there are so many people who think it's morally wrong to try to evade taxes, i.e try to avoid being robbed by the state. The recent Panama papers "scandal" showed just how common this stance is. Orwellian new-speak terms such as "tax ethics" are thrown around in media. Tax evaders are portrayed as literally Hitler. But I wonder if it actually isn't the contrary that is true; that you in fact contribute to less evil if you evade paying taxes. Considering that it will mean less power to a morally corrupt state that steal, threaten, coerce, jail and bomb the shit out of people.
Is it morally wrong not to pay taxes then? No, not really. On the contrary. Refusing to be robbed is honorable. Just like @LarkenRose says in his speech below, taxpayers in Nazi Germany were contributing to anything but good; they funded oppression, war and genocide. It was the tax evaders and smugglers who were the good. Exactly the same standards apply today.
The more you evade taxes the less you pay for the wars in Afghanistan, Libya, Iraq, etc, the kidnapping of drug users and other victimless "criminals", the monitoring of internet, crappy public schools and hospitals, the bloated, counterproductive and inefficient welfare state and government spending in general.