Risk to tax-take as technology makes it easier for firms to work across borders and move corporate activities.
The G20 group of leading industrial and developing countries was talking tough at the weekend about getting multinational corporations to pay more tax.
"We are determined to develop measures to address base erosion and profit shifting, take necessary collective actions and look forward to the comprehensive action plan the OECD will present to us in July."
It is an issue tailor-made for populist tub-thumping by politicians, from British Chancellor of the Exchequer George Osborne to Labour's revenue spokesman, David Clark, who hailed an OECD report on the issue, released last week, as revealing the "shocking extent of multinational tax avoidance".
The questions, though, are: how much of the problem is new and requires new policy responses, and how much of a problem it is in New Zealand?
Because what the report actually outlines is largely what we know already.
Multinational companies have long sought to arrange their affairs so that they recognise expenses in high-tax jurisdictions and income in low-tax ones.
They exploit the fact that tax systems treat debt differently from equity to debt-finance their operations in, say, New Zealand and generate lots of lovely deductible interest payments in the process. That is why we have thin capitalisation rules, which were significantly toughened in 2010.
They can use "hybrid" instruments, deductible in one country but exempt in another to gain a tax advantage. But when the New Zealand banks tried that they were, eventually, hammered in the courts under a general anti-avoidance rule.
"There's nothing new in this," says Robin Oliver of tax specialists OliverShaw, who for many years headed Inland Revenue's policy advice division.
"It's rust never sleeps."
In an era of long, border-crossing value chains, transfer pricing rules based on the arm's length principle are tricky to apply, especially when related to intellectual property (IP).
And more broadly in the age of cyberspace and e-commerce, a source-based approach to the taxation of foreign companies, grounded in concepts like having a substantial physical presence in the country, becomes a lot more challenging.
But before getting all indignant about the fact that people use Google and Facebook all the time and, look, they pay next to no tax in New Zealand, an important distinction needs to be borne in mind.
It is between trading with a country and trading in a country.
"Traditional exporters of goods and services do not pay income tax on their products in the country where the products are consumed," an officials' report last December on the taxation of multinational companies says.
This works both ways.
"New Zealand exporters will not usually be taxed in China on their profits from sales to Chinese customers.
"However, if the New Zealand exporter had more significant activities in China such as a manufacturing operation, a sales office or customer support services, China would be able to tax any profits associated with those specific activities."
The officials argue that the activities carried out by technology companies can be likened to exporters of goods who trade with New Zealand rather than in New Zealand.
"Since the bulk of what these companies do in terms of programming, designing websites, running servers and selling advertising space is done overseas, New Zealand, like other countries, may have very limited taxing rights."
If Google or Facebook employed a lot of people in New Zealand, raking in large sums from New Zealand advertisers, but offsetting that by payments for services of debatable value to their parent or sibling companies, that would be one thing. But that is not what their audited accounts show.
Google New Zealand's financial statements for calendar 2011 show just $4.5 million in revenue, almost entirely offset by marketing and other expenses, resulting in an tax bill of just over $100,000. Transfers between it and Google Ireland and other group companies amounted to just over $5 million each way.
Facebook's New Zealand numbers are even smaller.
Over the past few years New Zealand's corporate tax take has been near the high end of the OECD range, bettered only by Australia, Norway and Luxembourg.
Such crude comparisons need some caveats. Most countries do not have imputation credits, so that they get a second go at taxing company profits when they are distributed, and most do have capital gains taxes. So taxing earnings at the corporate level may be somewhat less important than it is here. New Zealand's relatively high corporate tax take may reflect a comparatively pure approach over recent decades - not offering tax breaks to attract foreign investment.
But we should not be complacent, Deloitte chief executive Thomas Pippos warns, as the corporate tax base in New Zealand, inasmuch as it relates to multinationals, will continue to reduce as their presence in New Zealand shrinks.
"With technological changes that make it easier to work 'virtually' and across borders, we have seen a lot of multinationals shift corporate or back office activities out of New Zealand."
This exodus of corporate activity is not new, he says, but has not yet run its course.
The converse, Oliver adds, is that we need to encourage IP companies like Xero to remain in New Zealand.
For Oliver, it is misguided to regard the desire to coax more tax out of multinationals as a collective problem requiring concerted action.
"The question should be: is every country doing all it should to actively protect its own tax base?" he says.
"I don't think the OECD has analysed the issues properly. It's just, 'Google pays no tax! We must do something!"'By Brian Fallow Email Brian