NSW Premier Dominic Perrottet has shut down the parliamentary term early, in a surprise move that ends all government business, including a local council probe under way in which his two brothers have been called in to give evidence.

Mr Perrottet has also appointed himself as finance minister to fill the slot left by former senior frontbencher Damien Tudehope, who resigned last week after revelations he owned shares in a company that won a slew of government contracts while he was in cabinet.