Corporate tax changes may top the list of issues for equity-market angst, but timing of enactment and details beyond the statutory rate may matter just as much as the adjustment. Former Vice President Joe Biden proposes raising the corporate tax rate to 28% from 21%, halfway back to 2017's 35% peak. A delayed phase-in seems likely to us, given economic distress. If enacted and effective in 2021, we calculate the Biden plan could shave 15% from the aggregated next three years of S&P 500 EPS. If delayed to 2023, the effect would be just over 3%.The median effective tax rate paid by the S&P 500 dropped to 20% in 2019 from 31.9% in 2018. Details, including potentially higher rates on non-domestic income and/or imports, and tax incentives for domestic production are as important as the statutory rate.