Schenge Rules

I can enter Portugal but will run out of the 90 days allowed in
Croatia. What to do then?

Leave the Schengen area immediately. Your plan includes a 60 day overstay, which is no joke. Expect a huge fine and a ban on reentry when you leave Schengen. And if caught during your stay, you will be deported.

This is very tricky...
If you are a NZ citizen younger than 31, you could qualify for a working holiday visa in Portugal, which would cover your stay in Portugal PLUS 90 days in the rest of the Schengen area, but that's a lot of hassle.

Or, perhaps simpler but you will need to do more research in your own, it seems that Portugal is willing to process extensions of stays beyond the 90-day limit, look here: https://imigrante.sef.pt/en/prorrogar-permanencia/vcd-iv/

This potential solution would imply that you reverse your trip and shorten the Croatia + Greece section so as to enter Portugal well within the 90 day limit (perhaps after 60-70 days MAX to allow for appointment and processing time).

I am otherwise unaware of any tourist visa that would allow for more than a 90-in-180-day stay.

As an EU passport holder myself, I certainly do not know all the tricks, so I will let others add whatever advice they may have!

Since Brexit has limited travel in the Schengen zone, I have been investing how to stay longer, but I haven’t found any easy solutions. You can pay €99 euros for a French 6 month visa (in addition to the 90 Schengen days) but you need to own a property in France! There is something similar for Spain but it costs significantly more.

I haven’t found any means of staying for 150 days. The penalties for not abiding by the 90 rule (including entry and departure days) are severe.

Basically you will need to reconfigure your plan to allow 60 days outside the Schengen zone. If you would still like to do all three, scale back your time and reallocate within 90 days (probably a few less than 90). then find time outside the Schengen zone.

This would include Montenegro, Bosnia, Serbia Romania, Bulgaria, the UK, and a few others.

29 days(to be on the safe side) or less in each place is the only option I see.

Reminder that NZ passport holders play by different rules

Actually the US has many of the same Bilateral agreements dating back to just after WW2. But this has always been a gray zone of working the Schengen limits. There really is little information on how to actually do this, and while many claim it is valid, I have not seen the experiences of those that actually have done it. Of the several travel forums I have been on, people have only reported success with Denmark (for US passport holder). As often as it is brought up on other forums, the concensus is that it is just not worth bothering with.

The link Balso posted above is the most complete "how-to" I have seen, but even that, Portugal may be doing that unilaterally, rather than within a bilateral agreement. I think the biggest risk is that despite your planning, at the time the extension is needed, they can always say "no", then your kind of stuck.

Tom is correct - it looks like I will have to move to NZ so that I can travel longer in Europe!

The article also says it is subject to the immigration officers at the airport being aware of the rules for NZ citizens and not just applying the 90 in 180 day rule. Notwithstanding, it appears not to apply to Croatia or Portugal and Greece is uncertain.

I (US citizen) deal with this every time I go to Europe. Unless there are loopholes open to New Zealanders that I don't have access to (and Tom_MN's post suggests that you do have options), you need to make major changes to your plans.

There are lots of non-Schengen possibilities on the Balkan Peninsula even though Croatia's status will change next month. Travel by public transportation in that area is slow, so you could spend a lot of time adventuring through countries like Romania, Bulgaria, Montenegro, etc; just stay out of Slovenia, Croatia and Greece. You could also go to Turkey.

There are flights to the very atmospheric Moroccan cities of Fes and Marrakech from many cities in Europe, so Morocco would be a viable destination for a chunk of your trip. All of the above would be considerably less expensive than heading to the United Kingdom or Ireland.

The one Schengen loophole I believe is easy to use--though I haven't tried it yet--is in Denmark. You can spend nearly 90 days in other Schengen countries, then go to Denmark and remain for 90 days. The documentation is linked from this webpage: https://www.nyidanmark.dk/en-GB/Words-and-concepts/US/Visum/Overview-of-Travel-Documents,-Visa-Conditions-and-Border-Crossing-Points/. The exception is explained beginning on page 15.

If you decide to take advantage of the additional-stay option that seems to be available to you as a New Zealander in several of the Schengen countries, you must be sure you leave the extra-stay country via transportation straight to a non-Schengen country. I'm also not clear on what would happen if you wanted to visit more than one of the loophole-offering countries after you hit the 90-day limit. Would France, for example, still admit you after 90 Schengen days followed by 20 extra days in Denmark??

It appears you are in a very fortunate spot as a holder of a New Zealand passport. But do research this carefully.

Thank you all for your input, especially a fellow kiwi, Brenontheroad!
It seems that with a NZ passport and the bilateral visa waver we have with European Schengen countries, the 99/180 rule applies to each country individually rather than the Schengen area as a whole. If correct, then no problem. However, each border control interprets ( or is not familiar) the rules differently and is likely to apply the 90/180:rule regardless. As Bren suggests, having something from the relevant Embassy's to show makes sense. Also, I could apply for a Schengen Visa to enter Croatia and Greece. More to investigate!

It seems that with a NZ passport and the bilateral visa waver we have
with European Schengen countries, the 99/180 rule applies to each
country individually rather than the Schengen area as a whole. If
correct, then no problem.

If you plan to do this, you need to be 100% sure that you are allowed to do it. And check with the embassies before you go.

Also, I could apply for a Schengen Visa to enter Croatia and Greece.

Unless the procedure is different for NZ, there isn't a formal application procedure. You turn up at the Schengen border and you get an arrival stamp. When you leave Schengen you get an exit stamp.

If you go directly from a Schengen country to another Schengen country you don't get a stamp - you don't even see a border official. You should be very sure that you understand how to activate your magic powers special status, so you aren't in trouble when it is time to leave.

I would advise caution. Some Comments:

It seems that with a NZ passport and the bilateral visa waver we have with European Schengen countries, the 99/180 rule applies to each country individually rather than the Schengen area as a whole. If correct, then no problem.

I will say not correct. Bilateral agreements are with individual countries and most pre-date the Schengen agreement going into effect for the select country. For example there are ~26 Schengen countries, New Zealand has agreements with 18 of them, the US has agreements with 10 of them. The agreements are referred to as "extensions", essentially allowing a member state to unilaterally extend the stay in only their country under the terms of the agreement. My understanding of how it is applied, is that once you have traveled within the Schengen area, you can apply for an extension, stay for the allotted time, only in that country, then you must leave that country directly, without passing through another Schengen country, and the 90/180 day rule still applies at any reentry to the Schengen area. Basically, this "exception" is honoring agreements that individual countries had in place before they became part of Schengen.

However, each border control interprets ( or is not familiar) the rules differently and is likely to apply the 90/180:rule regardless. As Bren suggests, having something from the relevant Embassy's to show makes sense.

Don't know "Bren", but I would phrase it as each border control agent will interpret your situation based on their experience and the evidence at hand, as well as guidelines established by their organization. Based on information from a guy on the internet (including me) I would not overstay the Schengen allowances and then show up at exit with a printout and argue with immigration control. The risk is a huge fine and a ban from reentry. What is sorely lacking for these exceptions is a clear process on how to acknowledge or apply with authorities to get the extension. As I mentioned, the link Balso provided, looks to be one of the better explanations. I would want more than a copy of the agreement, I would want an actual approval of extension.

Also, I could apply for a Schengen Visa to enter Croatia and Greece.

Terminology may be an issue here, but you are not eligible or can get a "Schengen Visa". Usually that term is applied to people from countries that have no Visa Waiver agreement with the body of Schengen Countries. Basically they have to go through an application process with one of the member states, to be granted a visa, which then does allow them to travel within the Schengen area, usually for the 90 in 180 days, or per the specific terms of their visa. New Zealand has a Visa Waiver. You can apply for something like a 6 Month extended stay visa with one of the countries, but the expectation is that you are establishing residency in that country, and need to show proof of that. Under that visa, you can travel to other Schengen countries, and even in and out of the Schengen area (if multiple reentry)

More to investigate

Indeed.

Based on information from a guy on the internet (including me) I would
not overstay the Schengen allowances and then show up at exit with a
printout and argue with immigration control. The risk is a huge fine
and a ban from reentry. What is sorely lacking for these exceptions is
a clear process on how to acknowledge or apply with authorities to get
the extension.

That is an important point, and you can't expect a Greek immigration officer to have detailed knowledge of Portugese-NZ treaties. That is a reason why the Danish "loophole" requires you to leave the Schengen area from Denmark. If you fly from Copenhagen to e.g. Boston, the immigration officer at Copenhagen airport will be aware of the rules (or one of their colleagues will be at least). But if you fly home via Schiphol, you'll most likely get fined for overstaying.

Thanks for all the helpful feedback to my query.
Would this plan work then?
Portugal for 42 days then say Uk or Montenegro for a couple of weeks to reset the 90 day clock.
Enter Croatia, stay 90 days, enter Greece, stay 30 days. Back to NZ.
thoughts?

No. Leaving the Schengen area only pauses the clock, it does not reset it.

If you leave Portugal (Schengen) to a non-Schengen country after 42 days you still have 42 days in the last 180. That doesn't change or reset. The only time that 42 days starts to go down is at day 138 when it starts to go down one day at a time, assuming you haven't spent any more days in that time in any Schengen country.

If, after the New Year, you spend 90 days in Croatia you have spent your entire allowance there, not even counting your 42 days in the bank already. You will be overstaying in Croatia after 42 (Portugal) + 48 (Croatia) = 90.

Understanding the 90/180 rule can be a bit tricky. But it is very easy once you get the hang of it. The important question is, in the last 180 days, how many of them have you spent in the Schengen area? If the answer to that question during any time of your stay is more than 90, you are overstaying.

So 35 days in Portugal and 40 days in Croatia, 15 days in Greece would work? I would be in Europe 4.5mths (135days) and would need to stay in a non-Schengen country for 6 weeks over that time? Suggestions?

Given where you will be, from Croatia, you could go into Bosnia-Herzegovina (Mostar for example) and into Montenegro for a couple weeks or more, or even go further afield into the Balkans.

Other than that, the UK or Ireland for a couple weeks would work.

Turkey might work with Greece, and near Portugal, Morocco would work.

So 35 days in Portugal and 40 days in Croatia, 15 days in Greece would work? I would be in Europe 4.5mths (135days) and would need to stay in a non-Schengen country for 6 weeks over that time?

135 minus 90 is 45.... so 6 weeks and 3 days. Remember that entry and exit days count as Schengen days too, even if only a few minutes or hours. Each time.

Also, with delays and cancellations all over the place, to say nothing of viruses. leaving several days slack is very wise these days.