How do I calculate W-2 additional withholding?

To calculate additional withholding on your W-2, first determine your expected tax liability for the year and compare it to the amount already withheld. If you anticipate owing more, you can specify an additional amount to be withheld from each paycheck. You can estimate this additional amount by dividing your expected tax shortfall by the number of pay periods remaining in the year. Consult the IRS withholding tables or a tax professional for precise guidance tailored to your situation.