the B is specifically the delta on the IP transfer pricing -- the IRS is saying the 2010 valuation of the intangibles moved to Ireland was too low, and then projecting forward what the income should have been attributed to the US entity under arm's-length pricing. it's not Meta's total ex-US income, it's the gap between what was reported and what IRS thinks a proper cost-sharing arrangement would have produced. the hard part for IRS is always that the 2010 valuation is inherently speculative -- Facebook was pre-IPO and the IP value is defined by future performance you can't know at transfer.