Labour MP Sue Moroney says Finance Minister Bill English has deliberately overestimated the costs of extending paid parental leave to six months to justify his decision to veto any increase.
Ms Moroney's Paid Parental Leave Bill would extend leave from 14 to 26 weeks by four weeks a year over three years. It is expected to have its first reading in Parliament tonight and has enough support to pass with the backing of all parties but National and Act.
In April, Mr English said the Government would veto the bill because it would require an extra $500 million in borrowing over the next three to four years.
But Ms Moroney obtained Department of Labour advice to Mr English in April which showed the estimated cost was $285.6 million over the three years.
The costings showed that in three years, the full 26 weeks' parental leave would cost $315.6 million a year.