In the past, employers had to routinely send the IRS any Form W-4
(PDF), Employee's Withholding Allowance Certificate, claiming more than 10 allowances or claiming complete exemption from withholding if $200 or more in weekly wages was expected.
Forms W-4 are still subject to review.
Employers may be directed (in a written notice or in future published guidance) to send certain Forms W-4 to the IRS.
The IRS also will be reviewing employee withholding compliance and you may be required to withhold income tax at a higher rate if notified to do so by the IRS.