Tiny Singapore does not look at first sight like one of Apple's priority markets: it has no official Apple Store and is not mentioned in the company's latest annual report.
Apple South Asia, however, its Singapore entity, booked US$14.9 billion in revenue for the 12 months to September 2012 - more than it would have received had the country's entire 5.3 million population each bought an iPhone 5S, an iPad Air and a MacBook Pro.
There is nothing illegal about the accounting practices employed by the computer giant, which, like many multinational companies ranging from Google and Microsoft Corp to BHP Billiton and Huawei Technology, uses the city state as a key hub for its Asia business.
Singapore has largely stayed out of the debate raging in Europe and the United States about the ways multinationals try to lower their tax bills.
But revenue-hungry governments are looking to impose tougher rules on so-called transfer pricing that could make it harder for firms to trade goods, services or assets between their Singapore and overseas entities.
As a result, accountants warn that the city state will need to review the level of transparency in its tax incentive schemes and get stronger justifications from companies on their transfer pricing arrangements to fend off challenges from other jurisdictions.
"Singapore's challenge is to ensure that it stands ready to adequately address any kind of unilateral tax action taken by other countries," said Abhijit Ghosh, a partner at PricewaterhouseCoopers in Singapore.
"In this brave new world of fiscal competition for the tax dollar, dispute resolution will be on the increase and Singapore will need to focus more resources on enforcing and defending its principles of value creation in international forums."
The government says it is against artificially contrived arrangements constructed "solely for the purpose of flouting or exploiting loopholes in tax rules", according to a spokeswoman from the Ministry of Finance.
However, Singapore is also arguing that it should not be singled out for its low tax rates.
Companies justify booking significant amounts of revenue and profits in Singapore by the fact they often run key business functions such as finance and operations, hold intellectual property rights there or base regional executives in the city.
Apple says its Singapore base includes finance, operations, online sales and customer support functions.
Singapore lures international companies with its reliable legal system, skilled, English-speaking workforce and high living standards. However, its low tax rates and generous tax incentive programmes are one of the biggest draws and have been a key driver behind the economic success story of the island.
The Group of 20 big developed and emerging economies has backed a draft plan from the Organisation for Economic Co-operation and Development that would give tax authorities greater rights to "re-characterise" transactions and ignore inter-company contracts if they believe they are aimed at channeling profits into low-tax countries.
Although its size pales as a consumer market in comparison with the likes of India or Australia, Apple's Singapore-booked revenues for the year to September last year exceeded the US$10.7 billion of net sales it recorded in the rest of Asia-Pacific, excluding China and Japan.
It recorded a post-tax profit on its continuing operations of US$186 million that year, with an effective tax rate of 6 per cent, according to filings lodged with Singapore accounting authorities.
Apple's Singapore operations featured in a US Senate report detailing how US firms structured their operations to book most of their non-US profits in low-tax jurisdictions. The report, published in May, described the circuitous legal trip taken by a batch of Apple products made in China and destined for Asian markets.
The "title", or legal ownership, of the shipment is bought first by a unit in Ireland called Apple Sales International, before being sold on to Apple South Asia in Singapore.
The Singapore unit, which is owned by another Irish entity - Apple Operations International - then sells the products to other Apple subsidiaries in Asia, third-party resellers or internet customers. The gadgets may never even touch Singapore shores, according to the Senate report.