In public policy, well-meaning but complicated ideas are often undone by a catchy name.

The U.K. had its "bedroom tax,¡± the U.S. its periodic battles over the "death tax.¡± Now it¡¯s Japan¡¯s turn, with the "singles tax¡± set to be imposed starting next month, part of financing for measures to boost fertility rates.

There are two substantial problems with the name, which originated on social media as a substitute for the less-catchy official term, the "Child and Child-Rearing Support Contribution.¡± The first is that it¡¯s not a tax, but an additional payment to public health-insurance premiums paid by all workers. The other is that it¡¯s not levied on singles ¡ª all contributors will pay the average of ?250 ($1.60) a month, set to rise in the future, regardless of whether they have children.