The building, home of the Waikouaiti Museum, now has a category 1 listing which is given to places that have a ''special or outstanding historical or cultural heritage significance or value''.
In the Waikouaiti area, the Matanaka farm buildings and St John's Church also have category 1 status Trust heritage adviser Heather Bauchop said the BNZ building, an early work of Dunedin architect Robert Arthur Lawson, was special as a rare survivor from an early period of New Zealand banking history.
The building was last upgraded, by the bank, in 1927, so it was relatively intact and visitors could still get a feel of what an early bank was like, as well as the life of its staff and manager.
The building was one of only four banks on the trust's register dating from before 1870.
The BNZ closed the branch in the 1960s and the building was given to the Waikouaiti Early Settlers' Association, which established the Waikouaiti Museum in 1966. Its collection includes the original counter from 1869, in the banking chamber.
