Treasury hired Goldman Sachs to run the ruler over state-owned KiwiBank and its future capital needs.
A spokesman for Treasury says the report has been completed but will not be made public because the details are commercially sensitive.
Confirmation of the report comes a day after KiwiBank and parent New Zealand Post posted their first-half results, which show banking propped up the barely profitable postal service, accounting for about 83 percent of the group's earnings.
KiwiBank's net profit rose 53 percent to $58 million as interest income gained 14 percent to $140 million.
Kiwibank chief executive Paul Brock yesterday told interest.co.nz that the lender was not yet generating enough profit internally to cover its ongoing capital needs.
The website says funding could come from a sale of debt or equity, with one possibility being the sale of a stake via a sharemarket float.