Los Angeles - Alcohol through LAX on transit?

Hello all. I'm new here so I hope I'm posting this question on the right place :confused:
I'll be flying from LHR to AUCK via Los angeles and I discovered that I need to pick up my bag and check it in again. Now, to New Zealand I can take up to 4 Litres of wine and 2 Litres of spirits but because of having to check the baggage again at Lax I'm now afraid that they'll make me pay huge tax on it, or even worse they'll confiscate it.
Does anyone know how this works, when you're in transit? Thanks!

Welcome to FT, xiribita!
If you're going to go through customs at LAX, if you have anything over 1L, declare it on the back of your customs form. There IS federal tax, but it's quite minimal so they don't bother collecting it. There are no limits on the amount of alcohol you can import in the state of CA nor is there any tax to be paid, so you will be ok, but do declare anything over 1L/pax.

Which airline are your flying? Depending on which, you may have to reclear security...meaning that you will need to check it.

Three points on bringing alcohol into the USA:

It's unlikely to be confiscated.
There's no limit on the quantity you're allowed in general, though there are sharp limits on certain types of alcohol that are considered dangerous (like absinthe) and on all products from designated countries (eg, Cuba). Unless you're bringing in items like these it's unlikely anything will be confiscated. Just declare what you bring.

You may have to pay tax.
The normal duty-free limit is 1L. Beyond that a tax applies, but charts at cbp.gov (Customs and Border Patrol) indicate it's small, on the order of $1-2 for hard liquor and less than that for wine and beer. Possibly because it's small, like Palal speculated, CBP seldom collects it. As a US citizen I've brought in 2-3L of alcohol on numerous occasions and have never been taxed.

You will have to check it in for your connecting flight.
You have to re-clear security when connecting from an international flight in the USA. The USA has low limits on the amount of liquid that can be carried in hand baggage. You'll almost certainly have to repack your liquor into your checked-in bags. That alone may discourage you from attempting to bring 6L of drink.

Another alternative is to buy the duty free at LAX and not LHR -- for most things LAX is cheaper (but LHR has far bigger selection at the high end). Or an even better idea is to buy duty free upon arrival at AKL (you can even get 25% discount if pre-ordered on the web). AKL is famous for having some of the cheapest liquor prices of non-Asian duty free stores, so it is a bit silly to carry it with you from LHR or even LAX for things that AKL stocks (which would be all the mainstream brands).

Which airline are your flying? Depending on which, you may have to reclear security...meaning that you will need to check it.

I'm not aware of any case in the U.S. where you would not have to reclear security after going through Immigration and Customs during transit. Definitely need to do so if transiting international-to-domestic. I'm less certain about international-to-international, though every time I've gone through Customs at LAX, I've ended up outside of security. Your airline(s) should be able to tell you. Yes, as noted above, if you do need to clear security you can't keep liquids over 3 oz. in your carry-on bags, so the bottles would need to be in your checked bags. You need to know this before you hand over your checked bags at the transit desk outside of Customs. My wife lost some cosmetic lotion she bought at a duty free store, and forgot about when we transited ATL. We'd handed over our bags and entered TSA security, to get to our ongoing domestic flight, when she remembered the lotion. Imagine having to pour out good booze you bought at LHR :-( I have never shopped at a LAX duty free store.

TSA requirement to reclear security for all international transits (the logic being that they don't trust the effectiveness of the security check at your departure airport, etc.). So it does not matter which airline is involved; NZ does have a sterile transit lounge at T2 but last I know while that avoided immigration/customs it still required a security check (and confiscation of liquids) at LAX. AKL is nice as you can buy cheap duty free upon arrival (prior to clearing immig/customs).