Shifting from one uncertain position to another, companies are facing a subtle but important change in how they must explain the effects of tax reform to their investors.

When it was signed into law in late December 2017, the Tax Cuts and Jobs Act produced the biggest change in tax rules that companies have seen since the 1980s. A drop in the corporate tax rate from 35 percent to 21 percent coupled with a huge shift in the approach to taxing foreign earnings produced an enormous learning curve for companies.