An op-ed by Morris Pearl in today's NYT argues the following: "With companies engaging in high-risk tax avoidance, the investing public needs more information, clearly expressed. Investors should, at a minimum, be given a list of all countries in which a company operates, the revenue and earnings attributed to each country, and the amount of taxes paid in each."
He argues that, otherwise, investors can't realistically evaluate tax risks, such as those in the Apple case. I gather that neither Apple nor its peer companies had pre-2014 financial accounting reserves for what's now clearly threatened by the EU state aid cases, because their advisors blithely thought there was no risk.
There are obviously more issues to consider with regard to Pearl's proposal. For one, would it further empower governments to challenge companies' tax positions? That might be good for the world, but is less good for current shareholders, who benefit if the positions aren't challenged. Note, however, that investors generally shouldn't mind, since a higher expected tax bill would presumably be built into the stock price at which they bought. Note also that OECD-BEPS may succeed in inducing some measure of country-by-country reporting anyway. (This ostensibly would not be public, but one would not be surprised if salient tidbits leaked out.) What's more there are already instances in current financial reporting practice of apparently sacrificing accounting accuracy for ethical / compliance reasons (e.g., not taking into account tax savings that have a less than 50% chance, even if well above 0%, of being sustained).
Companies no doubt will also argue - I don't know how credibly, as this isn't an area of personal expertise - that publicly reporting the information would give competitive advantages to rival companies, including those not facing U.S. reporting requirements, by revealing info about the scope and direction of their operations.
But the points in favor include not only that emphasized by Pearl - that otherwise investors may be under-informed about significant tax risks - but also the point, which has come out in accounting research over the last ten-plus years, that companies which engage in aggressive tax planning often turn out to have unexpected negative earnings shocks even if for wholly separate reasons. A company's international tax profile genuinely is and should be relevant to investors for multiple reasons, and it doesn't appear that financial reporting to date has done all that it could have to inform investors properly.