IRS Releases Publication 15 and W-4 Withholding Guidance for 2018 On January 31, 2018, the federal Internal Revenue Service (IRS) released Publication 15 — Introductory Material, which includes the following: 2018 federal income tax withholding tables. Exempt Form W-4. New information on: Withholding allowance. Withholding on supplemental wages. Backup withholding. Moving expense reimbursement. Social Security … Continued