The Government is being accused of abusing its power of financial veto, as legislation to overhaul the welfare system makes further progress in Parliament.
National hopes to save $1 billion by creating tougher work tests and moving 46,000 people off benefits in the next four years.
The Government on Wednesday vetoed a Green Party amendment that would have allowed Work & Income the discretion not to apply a benefit cut to a parent, if it would deprive their child.
The Greens say the move is an abuse of the power of veto and proves the Government has already budgeted for savings from its sanctions.
But Social Development Minister Paula Bennett says the change would have cost up to $300 million and was simply unaffordable.