The leaders of Canada's federal parties would have you believe that delivering on each campaign promise is carefully considered and achievable. But the leaders gloss over or dodge questions about how much those promises will cost taxpayers to deliver.

Today's Liberal platform announcement held few surprises, but it did, finally, put the "costing" question in the headlines.

The Liberals opted to provide a costing at the end of its platform, and it shows the party's plan is to spend $78 billion over five years. There was even a line about how some of it will be paid for – a new 15 per cent tax hike on rich Canadians. There was no attempt to fudge that a Liberal government will continue to run significant deficits to pay for its many promises.

Justin Trudeau pointed out that the Parliamentary Budget Office (PBO) has reviewed the Liberal budget. And if you look at the PBO's analysis of that new tax on wealthy Canadians, you'll learn that it applies to anyone with a taxable income of more than $222,661.

That detail is in stark contrast with both the Conservatives and the NDP platforms. The NDP has released one PBO costing – on Pharmacare but has not released any other policy costs. The Conservatives insist the Parliamentary Budget Office (PBO) is reviewing its platforms.

The PBO's involvement in platform costings first began in the 2019 campaign. I checked on the PBO's website and found 11 Liberal program costings that the PBO reviewed. There are no Conservative Party platform costings.

Conservative Leader Erin O'Toole told reporters today, "We will update Canada's Recovery Plan when the PBO gives us the confirmation back." That led me to think the PBO has yet to do the work on the Conservative Platform.

I asked the PBO if the Conservative Party has submitted platform programs for a costing analysis and when that analysis would be completed. I was told that the Conservative Party controls the release of any and all information.

Today O'Toole tossed out another expensive promise saying, "Canada's Recovery plan we will invest billions in key projects that will put Canadians to work, cut commute times and reduce emissions." O'Toole gave no hint of how it would be paid for.

A Conservative release said the Liberal government has not spent billions of dollars, and the Conservatives will "unlock those unused dollars." O'Toole said the Canadian economy under a Conservative government would grow by 3 per cent a year for the next 10 years.

Trudeau picked on that number today. He called the Conservative plan "magical thinking" and said three per cent annual growth in 10 straight years has "only happened once in our history." And Trudeau said, "Let's be very clear, Erin O'Toole can say whatever he wants. If he doesn't show the numbers, why should Canadians believe him?"

Jagmeet Singh was in Montreal and he was asked when the NDP will release a costed platform. His answer was similar to O'Toole's. "We will be releasing more details," was all Singh would say.

By releasing a costed platform, the Liberals gave Trudeau easy lines to hold the Conservatives and NDP to account during Thursday night's French TV debate.