輸入品は高い課税対象だ。

。

Imports are subject to heavy taxation.

Literal

Imported-goods [topic-は] high taxation-target is.

課税対象 (かぜいたいしょう) is a compound meaning 'subject to taxation' — 課税 ('taxation') + 対象 ('target'). Simple topic-comment structure with economics-domain vocabulary.