The Liberal government has handed over previously unreleased budget projections demanded by the federal budget watchdog in a move that is raising even more questions about the math in the Liberals' first budget.

"PBO has received requested data from Finance Canada," said the Parliamentary Budget Office in a tweet with a link to a letter it received today from finance officials.

The public release of detailed figures comes after sources told CBC's Neil Macdonald earlier in the week that the Finance Department did have the data, but was demanding that if it were released to the Parliamentary Budget Officer it be suppressed.

This tug of war behind the scenes between the Finance Department and the watchdog began on budget day.

It was then the PBO noticed that while the government had released the total annual cost of the major themes of the budget for the next five years, it only gave detailed breakdowns of how those totals were reached for the next two years.

PBO has received requested data from Finance Canada <a href="https://t.co/0cFgF0abAm">https://t.co/0cFgF0abAm</a> <a href="https://twitter.com/hashtag/cdnpoli?src=hash">#cdnpoli</a> —@PBO_DPB

"We thought it would be useful for Parliament to have access to the full five-year costing because the budget is really the projection for the fiscal deficit for five years," Mostafa Askari, assistant parliamentary budget officer, told CBC News.

"One needs to have the detailed information to add them up to the bottom line, and I think it's important for Parliament to have that information," Askari added.

So on April 1, the PBO sent a letter to the Department of Finance asking for a breakdown of the eight major budget themes.

Today it got its answer.

The eight themes of the budget are areas of expenditure described by broad titles such as Help for the Middle Class, A Clean Growth Economy and Canada and the World.

Unanswered questions

The letter accompanying the data sent to the PBO today includes cost estimates for the missing years listed in the new Liberal government's fiscal plan. But those numbers are raising a series of questions that are not easily answered.

For example, the first budget theme, Help for the Middle Class, is an area that includes costs and revenues associated with the middle-class tax cut, the tax increase on the wealthy and the child benefit.

For this year and next year the federal government says it will cost about $3.6 billion a year to fund, when the revenues from wealthy taxpayers and costs associated with the breaks for the middle class are factored in.

In 2019 the cost of that budget theme drops dramatically to $2.5 billion, then $1.6 billion the year after and then down to $900 million five years out from budget 2016. But there is no explanation why the cost drops so much.

There are only few possible explanations: one is that the revenue from taxing the wealthy will rise enough to offset the costs; the other is that the program will be scaled back; or it could be a combination of the two, or something else entirely.

The total cost for all eight budget themes goes from $13.5 billion next year down to $7 billion in 2020, with no explanation why.

Back to Square 1

So while the Parliamentary Budget Office now has the figures it has asked for, it is still unable to complete the task it set for itself: evaluating the math in the budget.

A government official speaking on condition of anonymity, said there will almost certainly be fresh demands for information from the PBO to the Finance Department — which was already signalling it will not go any further in explaining its numbers than it did in its letter today.

"As you know the government of Canada has placed great importance on openness and transparency, and we welcome your independent review of the budget," said Deputy Finance Minister Paul Rochon in the letter.

"I would note that the April 5 due date established for the department's response to the request was extremely, and unusually, short — 1½ business days," Rochon added. "The department would ask that longer timeframes be established for future requests."

Finance Minister Bill Morneau was in Toronto on Friday where he was asked about the dispute over the missing data following an afternoon event.

"We are committed to working together with the Parliamentary Budget Office, it's an important institution. We are working together with them right now," Morneau said.