税金

How it works

This builds up a noun phrase before asking about it. 込みのこみの (included) attaches to 税金ぜいきん (tax) to mean “tax-included,” and の (of) links that whole idea to 値段ねだん (price) — literally “the tax-included price.” Then polite です (is) closes the statement, and the final か (question) turns it into a question without changing the word order.