The documents released Tuesday show that it costs the department $129,767 a year to rent office space in a building on Brunswick Street in Halifax.
The lease deal reached with the Cornwallis Park Development Association would see the rent jump to $143,000 a year over a 10-year period.
Dexter told reporters the deal would be pretty much "a wash" when higher taxes in Halifax and administrative savings are factored in.
He also pointed out that the lease in Halifax was signed in 2006 and would be renewed at a higher cost once it expires in January 2014.
"From the numbers that we see . . . and what I've said was that it would be cost neutral or slightly to the benefit of the government and that remains the case," said Dexter.
Government estimates show the total cost of renewed leases in Halifax and separate buildings for the Agriculture Department in Cornwallis and the Fisheries Department in Cornwallis would run between $142,300 to $152,000.
Last week Dexter put the Cornwallis lease file on hold while he reviewed it, following concerns raised by the opposition parties on whether the deal was good value for taxpayers.
On Tuesday, Liberal Opposition Leader Stephen McNeil said the documents showed that the lease should have been put to tender so that taxpayers could be assured they were getting the best deal.
"What we don't know is whether it was actually the best deal for taxpayers because they would not follow what should have been proper tendering practices by putting it out there," said McNeil.
Progressive Conservative Leader Jamie Baillie said the deal should now be the subject of an independent audit by the province's auditor general.
"I think the time has come to take this out of the government's hands and protect the taxpayers interests by making sure that someone independent of the government does a review," said Baillie.