List of possible factors that make a form invalid. 1) The employee has provided false or incomplete information on the W-4. 2) The employee requested withholding for more than 10 allowances. 3) The employer requested additional information from an employee who submitted a W-4 form with fewer than three withholding allowances. 4) The employer withheld taxes based on estimates, rather than actual salary and wage amounts, and then submitted an amended W-2(previous employers)for that period to reflect. 5) If an employee verbally indicates that the form contains false information.