[starwed]

The reason it is immoral to pay taxes is that you are still benefiting from the existence of the government but putting the burden of supporting it on others.

You personally may agree or disagree with this, but that's what someone probably means when they say it is immoral to avoid paying taxes, even if it is perfectly legal. Taxes are part of the general social contract of our society, and aggressively finding ways to avoid paying them tends to a tragedy of the commons type situation.

[jakeonthemove]

You're thinking at country level. If you expand the thought to global level, the supposed immorality disappears - in this case, the taxes are just paid in another country, at a lower rate, but it still helps a part of society...