Optimize your W-4 withholding. Enter salary, filing status, and adjustments to see recommended per-paycheck withholding.
Update when you have major life changes: marriage, divorce, new child, new job, or significant income changes. Also update if you received a large refund or owed a lot.
Line 4(c) on Form W-4. This is extra money withheld per paycheck beyond the standard amount. Use it to cover tax on other income or to ensure you don't owe at filing.