Where changes do not affect the amount of tax to be withheld until the next calendar year (i.e., death of a spouse or dependent), the employee shall amend Form HW-4 filed with the employer on or before December 1 of the year in which the change occurs. If the change occurs in December, the employee shall amend Form HW-4 within ten days after the change occurs.
If an employee no longer qualifies for a complete exemption from income tax withholding, an amended Form HW-4 shall be filed to reflect the change and allow for withholding of taxes.
Haw. Code R. § 18-235-61-09