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If an employee has a change in marital status or (don't forget to also complete the Newly Married Checklist!) or just wants to change the options chosen on the W4 to adjust the amount of monthly Federal Tax withheld, the employee needs to complete a new Form W4. A new W4 can be submitted at any time; however, the W4 needs to be received by the last day of any given month in order to affect the following month's paycheck.
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