The main problem is that the objection rests on the inadequate foundation of libertarian entitlement theory. This political philosophy is badly misguided, for the many reasons outlined here and here. In particular, I argue here that there is no way that one could justly acquire an absolute property right over any natural resource. This then provides a libertarian justification for redistributive taxation towards a universal basic income:
it is the 'ground rent' or compensation that is owed to each human being for the land and natural resources that have been deprived them by others' illicit appropriations. All property derives from these ill-gotten gains, and compensation must be paid accordingly.
The second justification for taxation is to remedy market failures with regard to "externalities". To adapt an argument made in a recent post (though in a somewhat different context):
It highlights two major trends of the modern economy: (1) the "spread of significant environmental externalities"; and (2) the development of wealth "held in the form of information rather than material goods". What these trends have in common is that "they greatly enhance the importance of property rights which are extremely difficult to define and enforce." Van Parijs continues: "[I]t seems safe to predict that these trends will persist, and hence that it will become increasingly difficult to make sure that whoever is responsible for wealth destruction/creation actually pays/is paid for the damage/benefit caused."
Redistributive taxation is a fairly blunt instrument in this case, though its egalitarian nature might help to smooth out some of the arbitrary disparities caused by the malfunctioning market. But a better argument would highlight the need for specific taxes which target externalities. This justifies extra taxes on petrol, carbon emissions, garbage, and all other pollutants. Such taxation is manifestly just, for it ensures that people are responsible for the damage they inflict, rather than offloading the costly consequences of their actions on to others (including future generations).
A third justification for taxation is communitarian in nature. Wealth is not created in isolation, it is as much a product of society as it is the individual. After all, society provides the enabling conditions for the individual to flourish -- your success would not be possible were it not for the opportune conditions of the society one works within, and the actions of your fellow citizens. Thus the community might rightfully claim "dues" on wealth that is created within the safety of its confines. Wealth is a social product -- a fact which the atomistic view (common to liberalism and libertarianism) leads us to overlook.
(I think there are actually two arguments here which I am in danger of conflating. First, society is a precondition for individual flourishing -- so even if you create wealth yourself, you couldn't have done it without the prior benefits bestowed upon you by society. Secondly, wealth is a social product: you don't just create wealth yourself, it is a product of your interactions with other social agents, etc.)
These latter arguments take us beyond the theoretical apparatus of libertarianism, but, given the inadequacy of the theory, that's not a bad thing. Indeed, I think the libertarian has framed the debate in a very misleading fashion. They treat property as if it were a natural (pre-political) right, emerging from the 'state of nature', with which government may not interfere. But natural rights are a political fiction -- "nonsense on stilts", as Bentham put it. We have no reason to think that such bizarre entities exist. (We can ground morality just fine without them -- see my recent post on constructivist non-cognitivism.)
We should instead understand rights - including (conditional) property rights - as emerging out of a social/political context (and justified on indirect utilitarian grounds). On this more holistic view, you cannot see pre-tax income as your "natural" or "deserved" earnings. 'Pre-tax' is a misnomer: tax is not an imposition on some prior economic system, it is a fundamental part of the system. A sales tax is simply part of the price of what you buy. Income tax is just a factor that determines your earnings. "Ownership" is not a natural relation between you and an object, but a social relation between fellow citizens: it is an agreement to refrain from interfering with the socially-recognized (i.e. "post-tax") holdings of each other.
Some libertarians even go so far as to claim that taxation is equivalent to "forced labour". This absurd claim is a result of their atomistic (mis-)conception of the issue. They see labour as natural and prior, and taxation as a subsequent imposition on this natural order. But in reality, work is embedded within (and not prior to) the social context. We know in advance what the tax-rate is. When we agree to work, we agree to a taxed wage -- like I said above, the tax is simply part of the cost, it's something one consents to as part of the social transaction. There is no "force" involved, and no "theft". Of course, if you later refuse to pay the agreed cost, then the tax collectors will come knocking at your door. But try reneging on your debts to anyone else and see how they react!