IRS FAQ on Payroll Withholding Changes
On Thursday, January 11, the IRS released Notice 1036, updating the income tax withholding tables for 2018 in response to the new tax law. They also released Withholding Tables Frequently Asked Questions (FAQ), available here: https://www.irs.gov/newsroom/irs-withholding-tables-frequently-asked-questions
According to a news release from the IRS, "Employers should begin using the 2018 withholding tables as soon as possible, but not later than February 15, 2018."
The complete news release is available on the IRS website: https://www.irs.gov/newsroom/updated-2018-withholding-tables-now-available-taxpayers-could-see-paycheck-changes-by-february