Tools in This Collection
W-4 Withholding Calculator
Calculate optimal W-4 withholding allowances and per-paycheck amounts for 2026
Tax Bracket Calculator
See your effective and marginal federal income tax rates for all filing statuses
State Income Tax Reference
Compare top marginal rates, flat taxes, and no-income-tax states for all 50 states
Bonus Tax Calculator
Compare the 22% flat withholding method vs the aggregate method for your bonus
Alternative Minimum Tax Calculator
Estimate AMT exposure from ISO exercises, SALT add-back, and exemption phase-out
Quarterly Tax Estimator
Calculate April, June, September, and January estimated tax payment amounts
Kiddie Tax Calculator
Estimate the unearned income tax on children's investment income above the threshold
Guides & Articles
Your Income Tax Filing Workflow
Filing income taxes accurately starts well before April 15. The best outcome — no surprise bill, no large refund you gave the government interest-free — comes from calibrating your withholding at the start of the year, checking it mid-year if your situation changes, and understanding how your income maps to the bracket structure.
Step 1: Set the Right Withholding on Your W-4
Most people file a W-4 when they start a job and never update it. That's often fine, but if you got married, divorced, had a child, took on a second job, or started freelancing on the side, your old W-4 is probably over- or under-withholding. Start with the W-4 Withholding Calculator to build a current picture. It asks for your filing status, dependents, other income sources, and anticipated deductions, then recommends either allowances or a flat dollar amount for Step 4(c).
Step 2: Understand Your Bracket
The Tax Bracket Calculator shows how your income layers across the 10%, 12%, 22%, 24%, 32%, 35%, and 37% federal brackets. Your marginal rate is what you pay on the last dollar earned — important for deciding whether a Roth or Traditional IRA contribution makes more sense. Your effective rate is your actual overall tax burden. These two numbers are almost always different, and conflating them is one of the most common tax misunderstandings.
Step 3: Factor In State Tax
Nine states have no income tax; others tax at rates up to 13.3%. The State Income Tax Reference covers all 50 states with current brackets, standard deductions, and filing thresholds so you can estimate your total combined burden, not just federal.
Step 4: Handle Bonuses and Supplemental Income
Employers withhold at a flat 22% on most bonuses, but your actual rate may be higher or lower depending on your total income. The Bonus Tax Calculator runs both methods — flat supplemental and aggregate — so you can see the difference and decide whether to ask HR to use a specific approach.
Frequently Asked Questions
How often should I update my W-4?
Update your W-4 any time your tax situation changes: marriage, divorce, new dependent, major income change, or starting a side business. The IRS recommends reviewing it annually. A quick run through the W-4 Calculator takes about 5 minutes and can prevent both surprise tax bills and unnecessary overwithholding.
Is the alternative minimum tax relevant for most people?
AMT primarily affects higher-income taxpayers, especially those who exercise incentive stock options (ISOs), have large SALT deductions, or have significant preference items. The AMT exemption for 2025 is $137,000 for married filing jointly, which eliminates AMT exposure for most middle-income filers.
What is the difference between marginal and effective tax rate?
Your marginal rate is the rate on your last dollar of income — the bracket you're currently in. Your effective rate is total tax divided by total income. If you earn $80,000 single, you're in the 22% bracket marginally, but your effective rate is closer to 14-15% because lower income portions are taxed at 10% and 12%.
Do I need to pay quarterly taxes if I have a W-2 job?
Generally no — withholding from a W-2 job covers your estimated tax liability. However, if you also have significant self-employment, investment, or rental income that isn't withheld, you may need to make quarterly estimated payments to avoid an underpayment penalty.
Should married couples always file jointly?
Filing jointly usually results in lower total tax, especially when incomes are unequal. Filing separately rarely benefits couples unless one spouse has large medical expenses (since the threshold is 7.5% of AGI, a lower individual AGI creates a bigger deduction) or one spouse is on an income-driven student loan repayment plan.