Companies Hazy on Reporting Tax in Earnings; IRS Rules Up in Air (1)

More than a year after passage of the 2017 tax overhaul, multinational companies like Nike Inc. and Walgreens Boots Alliance, Inc. still aren’t sure what the new rules mean for their bottom lines—setting up a bumpy ride through the upcoming earnings season.

Companies are still waiting for the government to answer questions about the law’s international provisions so they can calculate their tax bills properly. At the same time, an SEC rule that let them take a pass on reporting some post-overhaul tax numbers has just expired, so they have to report something.

They’ll probably have to keep adjusting those ...