This paper examines whether, and if so when, luxury tax is justifiable. After a characterization of luxury tax, I critically examine several arguments that have been or can be made in defence of luxury tax, including Ng’s diamond good argument and a variation of Frank’s positional good argument. I put forward an alternative, expressive argument, according to which luxury tax can help to create and sustain social norms that discourage conspicuous luxury consumption and display of wealth. I explain several ways (...) in which luxury tax fails to achieve the expressive goal and brings about unintended consequences. (shrink)