関税
かんぜい · kanzei · JLPT N1 · noun
customs
税 — grain radical 禾 + 兑 (exchange/phonetic)
税 combines 禾 (grain) with 兑 (exchange), which also hints at the sound. In ancient China taxes were paid in grain, so the character originally meant a levy of harvest given to the state. Its meaning later broadened to taxes and duties of any kind.