Free W-4 form calculator and tax withholding estimator. Fill out your W-4 for 2026 with accurate federal and state withholding. How to fill out W-4: enter income, filing status, and state; add OBBBA deductions (tips, overtime, car loan interest, senior); get Step 4c recommendations and side hustle gap filler for 1099 income.
The W-4, Employee's Withholding Certificate, tells your employer how much federal income tax to withhold from your paycheck. When you fill out a W-4 form, you provide your filing status, dependents, and other income so the employer can estimate your annual tax and divide it across pay periods. A W-4 calculator or W-4 assistant like this one helps you get the right withholding so you don't overpay (big refund) or underpay (owe at tax time).
For 2026, the One Big Beautiful Bill Act (OBBBA) added new deductions that affect withholding: no tax on tips (up to $25,000), overtime premium deduction (up to $12,500), car loan interest (up to $10,000 for US-assembled vehicles), and an extra senior deduction ($6,000 for taxpayers 65+). Use this W-4 form calculator to factor them in.
Update your W-4 when you start a new job, change filing status (e.g. get married), have a child, take on a side hustle (1099 income), or when tax law changes. For 2026, if you have tip income, overtime pay, car loan interest on a US-assembled vehicle, or you're 65 or older, submitting a new W-4 can lower your withholding and increase take-home pay without owing more at tax time.
If you have 1099 or gig income, use the side hustle gap filler in this W-4 assistant to see how much extra to withhold on Step 4c—or whether to pay quarterly estimated tax instead. Getting withholding right avoids underpayment penalties and surprise tax bills.
Step 4c (extra withholding) on the W-4 is where you ask your employer to withhold an additional dollar amount each pay period. Use it if you have other income (interest, 1099, spouse's income not withheld), want a larger refund, or need to cover tax on side income. This W-4 calculator shows recommended withholding per paycheck and suggests an amount for Step 4c when you use the refund vs paycheck slider or the side hustle gap filler.
Many states have their own withholding form (e.g. California DE-4, New York IT-2104, New Jersey NJ-W4). The W-4 Assistant supports all 50 states: select your state above and complete the federal W-4 first; the tool will point you to your state form and help you stay in sync so you don't over- or under-withhold state tax.
Take-home pay & withholdings
Take home pay H1B
Federal & state tax by state
Side hustle withholding
Social Security & Medicare
Tax on bonus income
2026 deductions & credits
Convert wage to annual