If you owe taxes, the government's actions to reclaim those don't constitute theft.

If anyone is stealing, in this hypothetical where you aren't paying your taxes, it's you, from the rest of us.

Why do you believe you have a ethical claim on my labor? Do you own me?

While there can be a case for Land taxation, there is no ethical claim for Income Taxation.

Then why is land taxation ok, but not income?

With any good or service, there is the same economic trace back to government subsidies. Your income comes from the trading of goods or services.

If you fail to pay your taxes to the government, and the government takes your land – you have to ask, where did you get your land from?

I own a house, if you trace back the chain of land ownership, the original title was issued by the government. (Where did the government get that land from? They stole it from the indigenous people.) When the government gave the first titleholder the land, they granted that title subject to the understanding that taxes would be paid and laws would be obeyed (including taxes and laws introduced after the original title was issued.) You can't give better title than what you have, so every subsequent owner, up to myself, has inherited the same obligation to pay taxes and obey laws. If the government's right to tax me is invalid, then my ownership of the land my house is built on is invalid too.

This would be valid if we were only talking about taxation applied to the actual land.

The scenario I described was the IRS taking your land to cover taxation based on your Income, IRS does not tax land in any way. They tax income and other transactions but not land.

The IRS however can take your home, car, or any other personal property you own to cover income based taxation.

I actually agree with your assessment for pure land taxation (not to include any structures, or other items you places upon the land)

Taxing land value I believe has a ethical foundation for the reasons you stated, taxing income has no ethical foundation for those same reasons. If you believe the government has the right to tax land because it has or once had an ownership interest over that land, then the only possible reason you could agree that the government has the right to tax income is if you believe the government has a ownership interest over your person.

When the government gave or sold the land to the first titleholder, it was not giving or selling absolute rights over the land – that is sovereignity, which governments usually don't sell or give up (although occasionally they do, e.g. Russia selling Alaska to the US) – it was giving or selling only partial rights. Even if it labelled the transaction "freehold", I think in reality all real estate is actually leasehold, with the government as the landlord, subject to lease conditions (laws) and rent due (taxation). It retained the ultimate ownership of the land, and only sold/gave a limited and subordinated form of ownership.

Suppose someone wants to lease land, and make the rent proportional to the tenant's income. You might think it is an odd arrangement, but freedom of contract implies if landlord and tenant agree on this it is binding. Now, that essentially describes income tax. The government owns all its territory, it has leased it to the residents of that territory, it has made the rent (tax) proportional to income. If you don't pay your rent, the government can seize your moveable property, just like how your landlord can seize your moveable property if you don't pay your rent. (Unpaid rent is a debt, and its collection can be compelled through the same legal processes as any other debt.)

That argument doesn't follow at all.