The new W-4 can be filled out by answering the questions about your marital status, age, income, and adjustments. You can find the instructions for these forms from IRS.gov or your local sate website. The W-4 uses the information entered to determine your taxable income for the year which in turn shows what tax bracket you will most likely be in. This number is used to determine the percentage of withholdings for each w-4 submitted per job.Using TurboTax W-4 calculator can make this easier. By answering the questions and using your last pay stub you can determine what to enter on the W-4 and even how to adjust it to get your desired end result during tax time.
https://turbotax.intuit.com/tax-tools/calculators/w4/