Stephen Harper pitched the plan during the 2011 election campaign as "one of our highest priorities" once the budget was balanced. Since then, the Harper government has repeated many times this electoral promise.
But a day after tabling the federal budget, confirming it will be in the black next year, Flaherty raised serious questions about the plan to allow families with children under 18 to split their household income of up to $50,000.
"I'm not sure that overall it benefits our society," Flaherty said in his first post-budget event, saying the policy "needs a very hard analytical look."
He later elaborated. "It's an interesting idea. I'm just one voice. It benefits some parts of the Canadian population a lot. And other parts of the Canadian population virtually not at all," Flaherty told reporters following the event.
Flaherty is right: an analysis of the $3 billion Mad Men giveaway shows the Conservative plan is skewed heavily in favour of the wealthiest, with the vast majority of families (86%) receiving no benefit at all.
Watch Flaherty expose this Conservative family split: