You need to be on Sage 2018 or higher and install payroll 2.20. If you do a search there was a thread on it awhile back.

The PR 2.20 was modified to handle the new W4.  In employee maintenance on the Tax Tab there is a Deduction Amount instead of Deduction Exemptions based on the W4 worksheet.   There are also new filing statuses in the lookup dedicated to 2020 to handle the W4 criteria. For New employees hired after 1/1/2020 or existing employees that want to change their W4 will will need to use the new filing statuses and amount fields per IRS.  For existing employees that are NOT changing their W4, the PR 2.20 will still calculate based on the prior selections.