The IRS released Notice 1036, which updates the income-tax withholding tables for 2018 reflecting changes made by the tax reform legislation enacted last month.
The updated withholding information, posted on IRS.gov, shows the new rates for employers to use during 2018. Employers should begin using the 2018 withholding tables as soon as possible, but not later than Feb. 15, 2018. They should continue to use the 2017 withholding tables until implementing the 2018 withholding tables.
More information is available in the IRS Withholding Tables Frequently Asked Questions.