Yes bitcoin has a tax everytime you are going to make an transcation using pear to pear or person to person as you can see every time you are going to send bitcoin the tax are input in the transaction details or every time you are going to withdraw your money or exchange it into fiat currency. Hoping that goverment will not impose taxes soon.
I think it is transaction fee, not tax. whenever you are doing a transaction. It is different from tax because transaction fee can be adjusted according on how fast you wanted your transaction to be confirmed. With these , bitcoin does not have tax but fee. And the fee that is deducted from exchange is processing fee.
In my whole experience with sending and receiving Bitcoin, I never had seen tax or even transaction fees when I send or receive Bitcoin. I don't know where are you getting this kind of expenses. Because when I send Bitcoin to someone they received it exactly the amount I am sending them without any cost for its transaction. That is the good thing about Bitcoin because there is no cost for its transaction.