What's the deal with Facebook and tax?
The last known amount of tax social media giant Facebook paid in New Zealand was about $43,000: roughly the same amount a family-owned building company might pay.
Taxes are paid on profits, and in 2014 - the most up to date accounts we have - Facebook made a pre-tax profit of just $12,000 in New Zealand.
Its small tax bill pushed it to a $31,000 loss, but it's more interesting to poke around the rest of the accounts, as light as they are on detail.
Facebook New Zealand's income was slightly less than $1.2 million in 2014, earned for providing unspecified services to Facebook Ireland.
But its costs of doing business in New Zealand were only slightly less than this, leading to that tiny $12,000 pre-tax profit.
New Zealand had about 2 million active Facebook users, so these figures appeared to suggest each Kiwi only generated about 50 cents of revenue a year.
We also know, however, that at that time an Asia Pacific user was worth about $1.50 a head to Facebook: this number's now about $2.90.
Facebook makes the vast majority of its money from advertising, and in New Zealand it roughly costs about $10 to get your advertisement seen by about 1000 people.
So if Facebook New Zealand made its money providing services to Facebook Ireland, where did the advertising money spent by New Zealand businesses go?
One Wellington eatery, which did not want to be named, spent about $100,000 advertising on Facebook last year.
That's just one Wellington restaurant, spending slightly less than 10 per cent of what Facebook New Zealand claimed as its entire income for 2014.
They provided an invoice Facebook sent them for their advertising bill: it clearly states the restaurant was billed by Facebook Ireland.
So - and this happened around the world - Facebook's New Zealand advertising revenue appeared to go to its business based in Ireland.
Ireland has a 12.5 per cent corporate tax rate, less than half New Zealand's 28 per cent.
But Irish law also allowed for what was known as "the double Irish", a structure where two subsidiaries are registered there and one routes its revenue through a tax haven.
Facebook Ireland reportedly paid little tax as well, as it also made a small profit.
This was because of payments it in turn made to Facebook in the US and another company, Facebook Ireland Holdings, which was reportedly owned by multiple Facebook subsidiaries based in the tax-free Cayman Islands.
This was the "double Irish": revenue gets routed to Ireland, where corporate tax was much lower, where it then gets re-routed to another Facebook company based in a fully-fledged tax haven.
It is likely the Government is actually spending a lot more money advertising on Facebook than it is getting back in tax.
Last year, Government agencies spent at least $2.6m on Facebook advertising: the Electoral Commission, for instance, spent $270,000, while local councils often spent around $1000 each.
And globally, the sums involved are huge.
Facebook's value approached US$400 billion (NZ$574b) not long after it announced it made US$27.6b in revenue last year.
It paid US$2.3b of tax and turned a profit of US$10.2b - a figure higher than the overall market value of most of the companies on New Zealand's stock exchange.
In 2014, when it paid $43,000 tax in New Zealand, the parent company paid US$1.97b of tax.
The loophole was closing over the next few years as part of international efforts to crack down on sweetheart tax deals for multinationals, but it was all legal.