Acceptance of a bribe can occur after the performance of an act beneficial to the payer and without any expectation of payment when the act was done: Field v R  NZSC 129 (27 October 2011).
This is because  "it is simply wrong for an official to accept money or like benefits in return for what has been done in an official capacity."
And  an environment would otherwise be created where
"(a) an official who receives such benefits will come to expect similar benefits in the future and is likely to act accordingly; and
(b) members of the public who know about, or suspect, what has happened will come to believe that unless they too provide such benefits, they will not receive dispassionate consideration and, if prepared to provide such benefits, will receive corresponding advantages."
Any expressions to the contrary as might be detected in previous cases or law commission reports didn't matter.
" ... there is a fundamental inconsistency between the performance of official functions and the acceptance of private rewards for doing so. In large measure this is a corollary of the first reason in the paragraph above. But associated with this are related expectations about the way in which those in official positions, including Members of Parliament, can be expected to act. This consideration is also illustrated by the facts of the present case."
But there is room for courtesies:
" ... if there is an exception, it must address the extent of the gift and the particular context in which it occurs. We consider, therefore, that there must be a de minimis defence in relation to gifts of token value which are just part of the usual courtesies of life."
As to the element that a bribe be accepted "corruptly",
" ... In part it captures the requirement for a defendant to have acted knowingly. In the present case, this requirement required the Crown to establish that the appellant knew that the services he received were provided in connection with the immigration assistance he gave, meaning that he knowingly engaged in conduct which the legislature regards as corrupt. As well, it is the presence in s 103(1) (and like provisions) of the word "corruptly" which permits the de minimis exception to liability which we accept exists."