What do students, the mentally ill, and convicts have in common?
They all trigger the same exemption for tax purposes when your spouse belongs to one of those three groups.
You see, normally in Canada the lower income spouse is the one who must claim childcare expenses for income tax purposes.
The exception is that the higher income spouse may, in this exceptional situation, claim the expenses instead.
Of course I don't think many would automatically see humour in this - that all three categories get the same treatment. But when you're dealing with tax, I'll take a pathetic scrap of meagre comedy whenever I can.