The government announced the move to the library of the Lester B. Pearson International Peacekeeping Training Centre on Monday, but didn't release the financial details.
The cost of the lease was revealed after the Liberals questioned Fisheries Minister Sterling Belliveau in the legislature.
Department official Brett Loney said the 10-year untendered lease with the non-profit Cornwallis Park Development Association would cost the province $289,000 a year. Loney said the lease was for the 8,000 square foot office space as well as a nearby garage and compound.
Earlier, Belliveau told reporters he didn't know how that cost compared with the current lease for the department's building in downtown Halifax, which expires in 2015.
Loney said that information would be released on Wednesday.
Meanwhile, Belliveau defended the untendered arrangement.
"To me, it was the right thing to do because we wanted to make sure this was happening," said Belliveau. "We committed to this to be a very aggressive timeline and if we went into the tendering process you can appreciate the length of time that would incur."
Liberal Leader Stephen McNeil said the government should have issued a tender to ensure that it was getting fair market value.
He also said he didn't buy the ministers' explanation that there needed to be a quick timeline.
"This is a government that decided it was going to move departments overnight without any thought to what it meant to movement of labour forces or whether or not they are going to save money," said McNeil.
Progressive Conservative Chris d'Entremont said there would be additional costs incurred because the government still holds the lease for the property it is vacating in Halifax.
"Who is going to be paying for that space while it sits vacant? We are, the taxpayers of Nova Scotia," said d'Entremont.
The government said 20 full-time jobs would be moved with the fisheries headquarters, which would also share space in Cornwallis with regional staff from the departments of Agriculture and Natural Resources.
The new office is expected to open next summer.
The move is part of a government program to shift some government jobs from Halifax to rural parts of the province.