An advertisement endorsing outgoing Air New Zealand boss Christopher Luxon as a potential National Party leader should have had authorisation from the National Party, according to the Electoral Commission.
But the body says it will not be taking the matter further.
Last month, the Weekend Herald featured a half-page ad which compared Luxon to former Prime Minister John Key.
Underneath the caricatures of the two men were two hashtags: "#Luxon2020' and '#National2020'.
It was later revealed property developer Steve Brooks had paid for the ad but did not have National's authorisation.