Whalen is forecasting a deficit of $274.5 million for the 2014-15 budget year in her latest fiscal update, which is $4.5 million less than projected in the budget in April.
But Whalen said Monday that to keep the Liberal government's fiscal plan on course, she had to make a mid-budget adjustment that would reduce spending by about $30 million. The changes cut department spending by one per cent and reduce civil service hiring over the rest of the 2014-15 fiscal year.
Whalen said the move was needed after it became clear government departments were not able to meet the one-per-cent cut included in April's budget, which was supposed to produce $28 million in savings.
"There were reductions made but then there was a recognition of costs that hadn't been properly budgeted," said Whalen. "It was a more cumbersome process and this time we're simply going to give them one per cent less."
She said while revenues are expected to increase by $6.8 million since the spring due to personal and corporate income taxes and petroleum royalties, they are expected to be offset by a decline in revenues from the Harmonized Sales Tax, as well as gasoline and tobacco taxes.
Whalen wouldn't tip her hand, but she warned again that maintaining revenues will be challenging and as a result some "big choices" will have to be made, beginning with next spring's budget.
"There have to be some serious cuts and changes," she said. "It's very important for Nova Scotians to understand that we can't continue to operate on deficit financing."
Whalen said one of the unexpected costs since April stems from the operator of the Nova Star ferry receiving the remainder of a $21-million loan that was meant to be spent over seven years.
Asked if the government would provide more financial help for the new ferry service between Yarmouth, N.S., and Portland, Maine, Whalen said the Treasury Board hasn't received any requests.
"We have a commitment to the Nova Star," she added. "We believe it needs certainly more than the time it's had to prove itself."
Tim Houston of the Progressive Conservatives said the government's numbers indicate it doesn't have a plan to turn the province's economy around.
He labelled the projected deficit and adjusted net debt figure of $15.1 billion "job killers."
"They overspent and we're hearing about a bit of a shell game to move some numbers around. It's a reaction to some mistakes that they've made."
The NDP's interim leader, Maureen MacDonald, also dismissed Whalen's assertion that cuts would be needed in the future, saying that won't fix an economy that's shed thousands of jobs in recent months.
"There's been too slow economic performance in this province ... and that's the problem we need to tackle collectively," said MacDonald.
The next budget update is scheduled to be released in December.