Finance Minister Michael Cullen claims National's tally of spending promises so far will cost in the region of $5.5 billion.
Added to that would be another $2 billion to fund its tax cuts, Dr Cullen said in speech notes for delivery this morning.
He said National had already committed to
extra spending in areas such as roading, prisons, law and order, defence and aged care.
That would mean National would need to cut spending in other areas by the same amount - plus another $2 billion a year to pay for the tax cuts they were leading people to expect.
"Yet they still claim that basic services will not suffer. This defies logic."
National finance spokesman John Key said Cullen's numbers were "wildly inaccurate" and he should wait until National rolls out its full policy.
National is still to announce its income tax cuts package, and is holding off until after Prime Minister Helen Clark announces the election date.
But the Government has been claiming for a long time that National would cut core social spending to pay for tax cuts.
Dr Cullen's speech notes said it was inevitable that National's spending cuts would have to go beyond the core Government departments and attack social services like pensions, health and education.
"There is no alternative if they are to find the $7.5 billion of cuts they would need," he said.
"No one should be under any illusions as to where these cuts would bite - pensions, health and education."
