Thanks guys. I'm not applying for a medical field, I am a policy officer. The only government department that have mentioned it in any of the jobs I have looked at so far is the Ministry of Health and it's on a general form for all jobs so I wonder if it is because they often employ people in medical roles. Ministry of Social Development haven't mentioned it for instance, nor the Law Commission. For most policy jobs (with the exception of super specialist positions) they want you to have a degree in a vaguely useful subject - I have an undergrad and 2 post-grad degrees in Law so I fit that bill.
From memory for the job I'm applying for they want a tertiary qualification in law - I have 3 of those, so I more than meet the requirements.
They only say the qualification MAY need to be reviewed before an offer of employment can be confirmed - not before you are offered a position. Also I'm confident that my qualification, if assessed, will be confirmed and that they will meet the requirements of the role.
So, on balance I don't think I'm going to get them assessed unless I'm asked to as I may not need it (I'm not convinced I have that good a chance at this job) and tbh I don't have a spare $780 at the moment which is what it costs!