Great question! Since this change will reflect your current year taxes and alternate each year I would definitley update your W4 form with your employer to account for the most up to date tax situation for you. Besides updating W4 form with your employer I would use a tax calculator. TaxCaster is a good one and I will add a helpful article on how to estimate federal withholding.
TaxCaster
How to Estimate Federal Withholding
W4 Calculator
