Two years ago the government decided not to boost to the accommodation supplement because of fears landlords could pocket the extra money, and rents could be pushed up.
However, ministers have since changed their mind, introducing an increase of up to $80 a week for some families in last week's Budget.
The changes are to due to come into effect from next April. People who would benefit the most are those on lower incomes living in cities like Auckland.
But advice from officials from the 2015 Budget showed the decision was made not to raise the accommodation supplement that year because they could not be sure tenants would get the benefit of the extra money.
The concerns about what were described as "landlord capture" were contained in advice from officials at the Treasury and the Department of Prime Minister and Cabinet.
The Prime Minister Bill English said raising the accommodation supplement was unlikely to push up rents, despite earlier advise to the Government that it would.
Mr English told Morning Report he was not expecting landlords to raise rents and the move was needed to help meet the needs of families.
Property investment advisor Olly Newland said tenants should expect a better standard of housing if landlords raise rents following the Government's increase in the accommodation supplement.
"It will be more benefit to the tenants who will have a better quality of home," he said.