This morning Boris is proposing a new tax concession, that "employees should be allowed to pay for their season tickets from their pre-tax income".
So it would exclude the lowest paid, who are below the rising income tax threshold, and it would exclude more low paid people who simply can't afford the outlay necessary for a season ticket, and it would exclude the low paid in temporary employment or on zero hours contracts.
Naturally the administration of it hasn't been costed, but it would seemingly rely on on-line self-certification. Great.
This is how the tax system gets more complicated every year. Ken Clarke has said that tax simplification is always a political non-starter, because the losers will always complain, and there are no obvious winners.
Nonetheless, Allister Heath is surely right that the economy would benefit from a simpler tax system. But what politician would forgo the glory of fashioning yet more tax concession headlines?