Amgen Inc. It could ultimately have to pay up to $10.7 billion in taxes, interest and penalties to the IRS, almost as much as the company’s total profits over the past two years. Coca Cola Co. could owe the IRS as much as $16 billion, about as much as its income for the past year and a half. Airbnb Inc. may have to pay $1.9 billion.

How much money have businesses actually set aside to prepare for the potential payment of these huge IRS bills? Not so much.

Coca Cola has set aside just 3%, or $465 million, of its potential giant bill. Amgen…