Big Tech Frets Over French Digital Tax Compliance Headaches

U.S. tech giants may face costs in the millions of dollars to get their systems ready to pay a 3% tax on their digital revenue in France.

The amount could include the price of rebuilding IT systems to identify French users from previously captured data. The measure was passed in July, but applies from January 2019—a factor companies have started flagging as a compliance problem.

The compliance problem could get more serious for companies if other countries implement digital measures of their own. The U.K., Austria, and other nations are eyeing similar taxes.

Facebook Inc., which reported 2018 global revenue ...