Michael MHK Alf Cannan says the government's claim that the books have been rebalanced is a myth.
Speaking during today's Budget debate, Mr Cannan claimed people were being misled.
He also voiced his concern at suggestions draw-down from government reserves to fund public spending had come to an end.
He presented a different set of figures which projected reserve spending of £77 million next year.
It's understood they include liability for public sector pensions and are not directly comparable to government figures, which refer to external investments and internal reserve funds.
Mr Cannan also labelled the Big Debate 'The Big Turn-Off' - an initiative he claimed which had not engaged public support for change: