Taxes are purely a construct of law though. The only reason it's immoral not to pay taxes is because it's immoral to break the law, at least if the law is just. But we're not talking about people breaking the law, we're talking about people obeying the law.
Think of it this way: if you can get an effective tax rate of x% by doing this and y% by doing that, and x < y, what's the moral difference between doing what you need to do to pay x% and the government changing the tax rate so you pay x% either way? It's not a question of what's the most moral percentage to pay in tax, it's a question of whether or not you're defying the law, which you aren't in either case. If the government lowered the tax rate to x% and you decided to cut out the middleman and just pay it, no one would howl at you to voluntarily pay more. So why do people howl at you for obeying other laws that allow you to effectively lower your effective tax rate to the same amount?
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.
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...
> The only reason it's immoral not to pay taxes is because it's immoral to break the law, at least if the law is just
Surely it's also immoral because it's moral to contribute to the society you benefit from, particularly when the laws are constructed to attempt to make you do so, even when there are loopholes?
If it had to do with contributing to the society around you, surely it would be the same obligation regardless of the tax laws, wouldn't it? Yet no one voluntarily pays more than the tax rate, and nearly everyone takes all the deductions and tax credits they can.
Right - the difference between the two is that deductions and tax credits are explicitly entered into the law to define what someone should be paying. The corporate tax rates that Apple pays in California are instead a reflection of the law's inability to effectively extract the money that society wants to - loopholes are involuntarily, while tax deductions are intended.
Of course it's often intended for a tax deduction to be okay. I'm not quite sure what the thrust of your argument is - are you trying to imply that loopholes as a concept are invalid?
Think of it this way: if you can get an effective tax rate of x% by doing this and y% by doing that, and x < y, what's the moral difference between doing what you need to do to pay x% and the government changing the tax rate so you pay x% either way? It's not a question of what's the most moral percentage to pay in tax, it's a question of whether or not you're defying the law, which you aren't in either case. If the government lowered the tax rate to x% and you decided to cut out the middleman and just pay it, no one would howl at you to voluntarily pay more. So why do people howl at you for obeying other laws that allow you to effectively lower your effective tax rate to the same amount?