In a news release, the IRS today announced that it anticipates issuing initial withholding guidance to implement the changes under the tax reform bill in January 2018.  Employers and payroll service providers are encouraged to implement the changes in February.  In the release, the IRS indicated that the withholding guidance will work with the existing Forms W-4 that employees have already provided to their employers.  Until guidance is issued, employers and payroll service providers should continue to use the existing 2017 withholding tables and systems.