Changes to the tax credit system could lift incomes of hundreds of thousands of families.

It follows a review of the $3 billion Working for Families tax credit system that ended last year which found “serious design issues” in the way some of the tax credits are applied.

Parts of it were released to our newsroom under the Official Information Act.

The Cabinet Paper launching the review says the Government was committed to making fundamental changes to Working for Families in the coming years.

Papers received by Newstalk ZB's newsroom show sector groups recommend broadening the number of families who receive the in-work tax credit, a payment of $72.50 a week for families with one to three children.

Social Development Minister Carmel Sepuloni told Newstalk ZB's newsroom the Government will continue to consider the advice it's been given.