A Bloomberg article mentions a special formula for taxing Apple that may be the source of the issue: "To comply with European rules, Ireland finally ended its

A Bloomberg article mentions a special formula for taxing Apple that may be the source of the issue: "To comply with European rules, Ireland finally ended its zero-tax policy in 1990. After that, Apple and Ireland agreed that the profit attributed to a key Ireland-based unit, the division discussed in Tom Connor’s letter, be capped using a complex formula that in 1990 would have resulted in a taxable profit of $30 million to $40 million." https://www.bloomberg.com/news/articles/2016-12-16/the-inside-story-of-apple-s-14-billion-tax-bill https://www.bloomberg.com/news/articles/2016-12-16/the-insid...