The "tax" part is what you pay above what the cost of a Product or Service would be if there wasn't a Monopoly, Cartel or legal structure forcing you to acquire that product or service.
The actual cost of making and/or providing that Product or Service (plus a bit of profit to incentivise somebody to actual do it) is the part that serves that purpose (and thus can be said to be "earmarked for a specific purpose"), anything above that is just money you are forced to put in the pocked of somebody for holding a dominant market position due to natural or artificial market barriers and/or even having bough politicians to tilt that market in their favor, killing the viability of alternative products or services or even legally forcing you to acquire that product or service.
That "above natural cost" part of what people are forced to pay for essentials like housing is not earmarked for anything (since it does not go into the costs of the other side to provide you that Product or Service or the profit margin needed to incentivise somebody to do it), plus unlike taxes payed to the Public it will never come back and provide you with any benefit and even in a Democratic system you have no control whatsoever over what it is used for unlike one's traditional taxes where theoritically (the more trully Democratic a nation is, the more it is so in practice) one has some influence in how it gets uses through the vote.
But sure, you can call the part that is used to actually pay the costs of the Products and Services plus a fair profit margin, to be a deduction if you want (personally I just think of it as natural cost of living). Personally I see that part as totally fair, so not at all an unfair burden, whilst more broadly politically I actually favor a system were life's essentials are take care of for all from the common pot which is the taxes paid to the public, in this specific point I'm restricting myself to a pure Trade logic.
Now we're getting somewhere.
The next part is this: what is there in Socialism to make sure that the period of Revolution is time-limited and if within that time limit the Revolution does not reach Communism, then the Revolution none the less ends?
Consider the following mental exercise:
If both cases started from a state of low freedom and during the Revolution the freedom is even lower, why would one situation be autocratic and the other not: they're both claiming to be Revolutions to reach a better system, they both never stop being in the state they call "Revolution" and in both the leadership can change and end up being people of ill-intent - they look the same, are both autocratic and both never end.
My point was never that Socialism has overtly or covertly ill intent or that it wants to create an autocratic state (I believe it's quite the contrary - it's genuinelly a political theory meant to produce the "greater good for the greater number"), my point is that de facto its a plan structured in such as way that the Revolution - which is as you admit a period of autocracy - it says is required to reach Communism never actually ends because it fails to reach Communism and has no mechanisms accept a less than perfect system than Communism after a while even if it's vastly better than the previous system) and end the Revolution. Meanwhile the power structures of the Revolution are captured by people with ill intent (who are the kind of people who seek power, especially the unrestrained power of a Revolution), which is how for example the Russian Revolution went from what it was under Lenin to the murderous psychopatic shitshow it became under Stalin.
Naive idealism in the original plan or incompetence in its execution, together with an unwillingness to let go create an ethernal state of autocracy called "the Revolution" - in other words an unending autocratic situation - just the same as ill intent claiming to be a Revolution does.
Absolutelly, all Revolutions are periods of autocracy. What makes some actual autocracies is that that stage never ends and there is no mechanism in place to de facto end it, even when the original intention was to end it but said end was conditional with reaching an objective which has never been reached in practice anywhere in the World.
If you can't exit Revolution in any what other than to reach a state which was never reached in the World, then de facto what you have is a process to create a neverending Revolution, not a process to reach a better state.