Three rules, all published, all easy to miss
Immigration New Zealand is unusually good about this: it puts its upload requirements on a public page rather than leaving them to be discovered through failure. The problem is that two of the three rules are not the ones people expect.
Documents must be PDF. Images must be JPEG or JPG. No Word documents, no PNG, no HEIC. That last one matters more than it sounds, because an iPhone saves photographs as HEIC by default, so a photographed document straight off a phone is the wrong format before you start.
The rule that fails silently: one document, one file
INZ states it with an example of its own:
"They must also be uploaded as 1 single file. For example, if your bank statement is 4 pages, it must be uploaded as a single file and not 4 separate files."
This is the one that catches careful people. You scan a four-page statement, you get four perfectly good PDFs, you upload all four, and every individual upload succeeds. Nothing objects. The submission is still wrong.
The fix is to combine them into one PDF before uploading, in the right page order.
The rule you cannot see for yourself
"Password protected or compressed files will be rejected by Immigration Online."
A password-protected PDF opens perfectly well on your own computer, because your reader has remembered the password. There is no padlock, no prompt, nothing to notice. Then it is refused, often without a useful explanation.
Bank statements are where this comes from. A great many banks issue statements protected by default, using your date of birth or part of your account number - and bank statements are exactly what a visa application asks for. If a document came straight from a bank's website, assume it is protected until you have checked.
If it is, remove the password and upload the unprotected copy.
"Compressed" does not mean what people fear
The word compressed in that rule causes real harm, because it reads as though reducing a file's size is forbidden.
It is not. INZ means container files - ZIP, RAR and the like. Making a PDF smaller so it uploads is entirely fine, and is often the only way to get a large scan through at all. What you must not do is bundle several documents into an archive.
What INZ does not tell you
There is no published maximum file size on that page, and this page will not invent one. Plenty of sites will quote you a number for New Zealand; none of them can show you where it came from.
What you can rely on are the rules INZ actually states: the two formats, one file per document, and no password protection. If an upload fails and you are within those, the size is worth investigating next - but check the stated rules first, because they are the ones causing most failures.
Before you submit
- Is every multi-page document a single PDF? Not several files that happen to be related.
- Did anything come from a bank, an insurer or a government portal? Those are the likely protected ones.
- Is any photograph still HEIC? Convert it to JPG.
- Are the pages in the right order, and the right way up? Merging is the moment that goes wrong.
You can check a file against these rules before you upload it, which is faster than finding out afterwards.