Sir Roger Douglas says the 2010 Budget is likely to be the best in more than a decade at controlling Government expenditure - but it will not go far enough.
The ACT Party finance spokesperson has issued a discussion document, which proposes cutting more than $3 billion of spending and lowering the top tax rate to 24%.
Sir Roger, who delivered five Budgets as Labour's finance minister in the 1980s, says current minister Bill English is going to stop the upward trend of spending.
But he doubts the 2010 Budget will put New Zealand on a real growth path.
To do that, Sir Roger says spending would have to be cut more, along with taxes.
He also says the Budget should open education, welfare and health to private sector competion.