I don't have sources, but just based on what I've seen and heard considering practical behavior FWIW.
The point of difference is not really taxes versus other expenses. The difference is whether you should give Maaser on Gross income or just on take home pay.
A reasonable argument can be made that theoretical money that you don't ever see, and don't have the choice to take or do with as you want such as FICA (or other mandatory deductions), was never yours and therefore you don't need to give Maaser on it.
This gets fuzzier with paycheck deductions you choose to make, for example if you have the option to have health insurance costs deducted from your paycheck or not, and you choose to do so, then it's more likely that would be considered your money that you need to pay Maaser on even though you never actually have that money in your hand.
I've never heard of a justification for not paying Maaser on take home pay that you have in your hand and then use to pay taxes such as sales tax or other expenses.
In practice it seems that if a person asks a shaila then a person's wealth level has a lot to do with the answer. A person with plenty of money is likely to be told to follow a stricter standard that results in more Maaser paid. A person who is struggling to survive from paycheck to paycheck is likely to be given a more lenient answer. There are people who have been ordered by their Rav not to pay Maaser at all because of their poor financial situation. As in any shaila CYLOR.