By Katie Kenny, RNZ Digital Explainer Editor

A month out from Christmas, the first of NZ Post's cut-off dates apply.

These deadlines allow presents the best chance of getting under the tree in time, depending on their destination.

If Father Christmas can deliver presents to the entire world in one night, why does it take so long for a box of chocolates to get to London? RNZ asked NZ Post to explain.

Sending cut-off dates

If you are sending Christmas gifts to Argentina, Bangladesh, Chile, or another country classified by NZ Post as "Zone E", the deadline for economy service is 25 November.

Yes, that's before Black Friday, on 29 November. An American import, for many this marks the start of Christmas shopping.

Economy items destined for Asia, Europe, North America, the South Pacific and the United Kingdom need to be sent by 1 December, or 2 December for Australia.

If you are posting within Aotearoa New Zealand, you have more time. The cut-off date for domestic economy items is 18 December.

And for international courier services? The deadlines are 8 December for Asia, Europe, North America, the South Pacific and the United Kingdom, and 9 December for Australia. (Note, some international destinations are not reachable by NZ Post's courier service.)

If you are willing to pay for the express service, sit back and relax: you do not need to have your items in the post until 11 December for Zone E countries, 13 December for Asia, Europe, and so on, and 16 December for Australia.

Of course, NZ Post acknowledges the cut-off dates are "targets only".

Domestic deliveries

Let's say I have dropped off an Auckland-bound parcel at my local post shop in Dunedin. South Island regional manager James Purdie tells RNZ what happens next.

A courier collects it and others and takes them to the local depot, where they are consolidated with other freight. That evening, they are trucked to Christchurch.

If I have paid for courier service, my parcel is loaded at Christchurch Airport onto a freight plane to Auckland. But if it is travelling via economy service, it is loaded onto another truck and driven to the top of the South Island, ferried to Wellington and driven the rest of the way to Auckland.

The parcels are unloaded at the operation centre there and sorted, Purdie continues. The final step is being loaded onto a van for delivery to the Auckland address.

Sorting, sorting

NZ Post has four automated sorting centres in Christchurch, Wellington, and two in Auckland. Sorting at other centres is done manually, based on the item's destination and how quickly it needs to arrive.

In the 2023 financial year, NZ Post delivered 84 million parcels, and 187m letters. That's 1.6m parcels per week.

The week following Black Friday is typically NZ Post's busiest of the year. In 2023, roughly 2.3m items were delivered nation-wide. That number is expected to be 2.4m this year.

"A lot of Kiwis take advantage of Black Friday [sales] for Christmas shopping," Purdie says. In response, NZ Post brings on extra people and extra vans.

International deliveries

Now, I'm posting another parcel, but this one is going to London. This is where NZ Post general manager export and international solutions Jared Handcock comes in.

My parcel arrives at the gateway in the early hours of the morning. (All items leaving the country via NZ Post fly out of Auckland.) It's screened and x-rayed to check it does not contain any dangerous or prohibited substances.

Only a small number of items are turned away at this point, Handcock says. A common culprit is perfume.

My parcel - which does not contain perfume - is scanned into a mail bag which in turn is scanned into an airline container. Within 12 to 24 hours, it's flown to its destination country. In this example, first to San Francisco and then to London directly.

"We service 130 destinations directly," Handcock says. "We do have other hubs; some smaller European destinations will be reached by truck from London."

After landing in London, all the items are handed over from the airline to NZ Post delivery partners, who facilitate customs clearance into the country and enter the items into their delivery network.

International express

The international express network is NZ Post's fastest - and most expensive - service, sending parcels, letters and documents to 220 destinations within one to five days.

From Auckland, express items are handed over to logistics company DHL, who take care of the rest of the delivery process.

Calculating cut-offs

During busy times of the year, NZ Post does a lot of planning based on updates from overseas delivery partners.

"We ask our partners when they need product, and work backwards from there," Handcock says. "The closer [the destination] to New Zealand, the more confident we are about the timeframes, as there are fewer touch points."

When items are sent to the other side of the world, NZ Post is typically allowing three to four days of additional transit time. The rest of the time is a buffer for customs and handling prior to entering the delivery network in the destination country.

Buying from overseas

If I've bought an item from an overseas retailer, how do I know if it'll arrive on time?

NZ Post also brings forward cut-off dates for inbound mail, Handcock says. To have any chance of landing on your doorstep by 25 December, international items need to arrive at NZ Post's international gateway and have received border clearance by 9 December for bulk mail and letters, 11 December for courier economy service, and 16 December for courier service.

Obviously, you need to buy your items well before those dates.

Final destination

Let's go back to Auckland, for a moment, where my friend is awaiting her gift.

I've given my friend a tracking number, so she can see when the parcel reaches the depot. After it has been allocated to the right courier, depending on where she lives, she will see an update saying it is out for delivery. It will be one of hundreds of thousands of parcels out for delivery that day across the country.

The final scan shows it has been left in a safe location, because my friend provided NZ Post "authority to leave" the parcel on her doorstep.

The parcel's final movement? From the threshold to under the Christmas tree.

"It's a pretty cool feeling," Purdie says, "delivering Christmas for New Zealand."