Martin Purdy writes:

Although an image of the Queen has graced the 'heads' side of New Zealand's coins since 1953, she did not appear on our banknotes until the introduction of decimal currency in 1967when the Reserve Bank issued its third series of banknotes. Her portrait has also appeared in each series following: Series 4, 1981; Series 5, 1991; Series 6, 1999, and Series 7, 2015. A short timeframe to prepare and print the Series 1 notes (1934), apparently prevented a portrait of King George V (reigned 1910 - 1936d) being included, while King George VI (reigned 1936 - 1952d) was not included in Series 2 (1940). The second Maori King, Tawhiao (c1822 - 1894), featured on each Series 1 banknote, while Captain James Cook (1728 - 1779) did likewise on Series 2. Both series were printed by De La Rue.

New Zealand was one of the last countries to switch to decimal currency. Dollars and cents replaced pounds, shillings and pence on 10 July 1967. Public interest in the introduction of decimal currency was high, and everyone had an opinion on the designs of the new coins and banknotes. The final note designs were tightly guarded by the Reserve Bank and released in June 1967, only a month before 'DC Day', short for Decimal Changeover Day. The Reserve Bank was keen to avoid giving any advantage to would-be counterfeiters wanting to con a public unfamiliar with the new genuine banknotes.

All six new banknote denominations were of different sizes and colours but had a very similar face design which was dominated by a stately portrait of Queen Elizabeth II, unsmiling but dignified, facing slightly to the viewer's left and wearing a tiara. Maori motifs and geometric patterns were added to enhance the design and supply the necessary security. This portrait of the Queen was one of the more widely-used throughout the British Commonwealth; being selected by five other countries to feature on their banknotes. The engraving was based on a photograph taken by London photographer Anthony Buckley several years earlier (on 19 October 1960) in the Blue Drawing Room of Buckingham Palace when the Queen was 34 years old. Some publications incorrectly state the photograph was taken at the time of the Queen's Coronation in 1953.

To read the complete article, see:
The Queen on New Zealand's currency(https://www.rbnz.govt.nz/hub/publications/bulletin/2022/rbb2022-85-01)

To read the earlier E-Sylum articles, see:
ELIZABETH II'S IMAGE ON BANKNOTES(https://www.coinbooks.org/v25/esylum_v25n24a29.html)
MORE QUEEN ELIZABETH II BANKNOTE PORTRAITS(https://www.coinbooks.org/v25/esylum_v25n24a30.html)