Sentence Correction (SC) | When calculating the annual tax deducted at the end of the year, it is

What is the source of this question ?
I find the reasoning very poor. How can one eliminate annual thinking it is redundant ? There could be other taxes as well. If this question is from an official source, it is ok and we can think about it. But if not then experts please help. Is actually annual redundant over here. I really don't find it convincing.

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