Frequently Asked Questions
Real answers to common tax and personal finance questions — with specific numbers, not vague reassurance.
Tax & finance questions
What's the difference between marginal and effective tax rate?
Your marginal tax rate is the rate on your last dollar of income — the highest bracket you reach. Your effective tax rate is total tax divided by total income — your average rate. For a single filer earning $75,000 in 2026: taxable income is $58,900 after the $16,100 standard deduction, putting the marginal rate at 22%. But the effective federal rate is only ~10.2% (~$7,670 tax ÷ $75,000 gross) because most income is taxed in the lower 10% and 12% brackets.
What is the Additional Medicare Tax and when does it apply?
The Additional Medicare Tax is an extra 0.9% on wages above $200,000 (single), $250,000 (married filing jointly), or $125,000 (married filing separately). Regular Medicare is 1.45% on all wages (no cap); the additional 0.9% kicks in above these thresholds. Employers are required to withhold it once wages exceed $200,000 regardless of filing status. For self-employed individuals, it is part of the SE tax calculation. Source: IRS Publication 15 (2026).
When is the 2026 tax filing deadline?
The 2026 federal tax filing deadline for personal returns (Form 1040) is April 15, 2027. If April 15 falls on a weekend or holiday, it shifts to the next business day. Filing Form 4868 extends the filing deadline to October 15 — but this is an extension to FILE, not to PAY. Estimated taxes owed must still be paid by April 15 to avoid underpayment penalties. State deadlines vary; most match the federal date, but a few (e.g., Virginia) differ.
Why do I owe taxes this year when I got a refund last year?
Common reasons: (1) You earned more — wage inflation pushed you into a higher bracket or reduced refundable credits. (2) You changed jobs or got a bonus — withholding on supplemental wages (22% flat) may under-withhold relative to your actual bracket. (3) Life changes — marriage, a second job, or a dependent aging out changes your tax picture. (4) You adjusted your W-4 — fewer allowances means less withholding. (5) Side income (1099, gig work, investment gains) had no withholding. Check your W-4 annually, especially after life changes.
Is my state tax refund taxable on my federal return?
It depends on whether you itemized deductions last year. Post-TCJA (2018+), ~88% of filers take the standard deduction — if you took the standard deduction, your state refund is NOT taxable. If you itemized AND the refund gave you a tax benefit (reduced your federal tax), then part or all of the state refund is taxable on this year's federal return (reported on Schedule 1, line 1). The $10,000 SALT cap (state and local tax deduction limit) means many itemizers got no benefit from their state tax overpayment, making the refund non-taxable.
How is my Social Security benefit calculated?
Social Security uses a three-step formula. (1) AIME: your highest 35 years of indexed earnings, divided by 420 (months in 35 years). (2) PIA: applied to 2026 bend points of $1,286 and $7,749 per month — 90% below the first bend, 32% between bends, 15% above. (3) Claim age: claiming at full retirement age (FRA 67) gives 100%; claiming early at 62 reduces benefits by ~25%; delaying to 70 increases benefits by ~24% (2/3 of 1% per month). Source: SSA.gov.
What's the 2026 standard deduction?
The 2026 standard deduction is $16,100 for single and married filing separately, $32,200 for married filing jointly, and $24,150 for head of household. It reduces your taxable income dollar-for-dollar. Source: IRS Revenue Procedure 2025-32.
Should I take the standard deduction or itemize?
Take whichever is larger. Post-TCJA (2018+), ~88% of filers take the standard deduction because it nearly doubled and the SALT cap limited state/local tax deductions to $10,000. You should itemize only if your total itemized deductions (mortgage interest + state/local taxes up to $10k + charitable contributions + medical expenses above 7.5% AGI) exceed the standard deduction ($32,200 for MFJ in 2026). Homeowners with large mortgages in high-tax states are the most common itemizers.
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How accurate are the calculations?
Formulas are 100% accurate against published sources (IRS Revenue Procedure 2025-32, SSA.gov, etc.). However, our models are simplified — they assume standard deduction (no itemizing), 27 states use full progressive brackets while 11 are approximated, and no individual credits. Real-world tax owed may differ materially. Always verify with tax preparation software or a CPA before filing.
What tax year is the data current for?
Federal tax brackets, standard deductions, and FICA rates are current for tax year 2026 (IRS Revenue Procedure 2025-32). State tax rates are current as of Q1 2026. We update annually each Q4 after IRS publishes new inflation adjustments. See our methodology page for the changelog.
Why does my actual paycheck differ from the calculator?
Common reasons: (1) Your employer withholds based on your W-4 which may include extra withholding or exemptions; (2) You have pre-tax deductions (401k, HSA, FSA, health insurance) not modeled here — see our methodology disclosure; (3) State tax may include local taxes (NYC, Ohio cities, Maryland counties) we do not add; (4) Year-end bonus or commission withholding uses different rules (22% flat federal).
I found an error. What should I do?
Please use the feedback widget (bottom-right of any page) and include: (1) the calculator URL, (2) your exact inputs, (3) the result you got, (4) the result you expected, and (5) the authoritative source you compared against. We investigate every report within 7 business days. Confirmed errors appear on the methodology changelog.
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Use the feedback widget at the bottom-right of any page, orcontact us. For the full math behind every calculator, see ourmethodology page.