Today we finished and published the new US Federal Income Tax withholding tables for the 2018 tax year.  The currently implemented rates are from Notice 1036 (Rev. January 2018), and are unlikely to change when the full Publication 15 is released.

These changes are the biggest I've seen, changing both wage bands, allowances, NRA, and wage band percentages. Check out the changes from 2017 to 2018 in this handy diff.

Setup

If you are already using the 2018 rates, all you need to do is pull the new code and upgrade the `l10n_us_hr_payroll` module to get the new rule rates.  You do not need to re-check any accounting configuration on the rules, only the calculations will change.