Editorial principles
- Every formula and figure is verified against official sources (laws and public agency notices).
- When rates change, the calculator and its guide content are updated together.
- Reported errors are fixed as soon as they are confirmed.
Calculators by Sin Dongho (178)
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Taxes
Renters Tax Credit Calculator
Estimate state renter tax credits. There is no federal renter's credit, but 11+ states (CA, MD, MA, MN, MI, VT, ME, WI, IN, NJ, MO) offer credits or deductions for tenants.
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Taxes
Small Business Quarterly Tax Calculator
Estimate quarterly federal tax for sole proprietors, S-corps, partnerships, and C-corps. Form 1040-ES, Form 941 employer FICA, FUTA, safe harbor rule, and QBI deduction.
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Taxes
Foreign Stock Tax Calculator
Calculate US tax on foreign stocks: ADRs, direct foreign holdings, foreign tax credit, PFIC §1291 punitive tax, NIIT, and FATCA Form 8938 reporting threshold.
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Taxes
Retirement Distribution Tax Calculator
Calculate federal + state tax + 10% penalty on retirement distributions. Traditional 401(k)/IRA, Roth qualified vs non-qualified, SECURE 2.0 exceptions, and bracket stacking.
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Taxes
Medical Expense Deduction Calculator
Calculate your medical and dental expense deduction on Schedule A: 7.5% AGI floor, itemized vs standard deduction comparison, federal + state tax savings. IRC §213.
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Taxes
Credit Card Rewards Tax Calculator
Determine if your credit card rewards are taxable: spending rebate (no), signup bonus with spending requirement (no), referral bonus (yes), bank account bonus (yes). 1099 thresholds.
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Taxes
Corporate Tax Calculator
Calculate US corporate income tax: 21% federal flat rate, 50-state corporate tax, 15% CAMT for $1B+ corps, 1% stock buyback excise, §174A R&E expensing under OBBBA.
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Taxes
Education Tax Credit Calculator
Calculate American Opportunity Tax Credit (AOTC) and Lifetime Learning Credit (LLC) for college, grad school, or job-skills education. MAGI phaseout, refundable portion, eligibility tests.
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Taxes
Charitable Donation Deduction Calculator
Calculate the federal tax savings from charitable donations: 60% AGI cash limit, 30% appreciated property, OBBBA $1,000/$2,000 above-the-line for non-itemizers, 0.5% AGI floor.
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Taxes
Dividend Income Tax Calculator
Calculate federal tax on qualified and ordinary dividends. 0/15/20% LTCG for qualified, ordinary marginal rates for non-qualified, plus 3.8% NIIT and Foreign Tax Credit.
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Taxes
Miscellaneous Income Tax Calculator
Calculate federal tax on misc income: rents, royalties, prizes, gambling, jury duty, hobby, survey research. New OBBBA $2,000 1099-MISC threshold and 90% gambling loss limit.
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Taxes
Gig Economy Tax Calculator
Calculate self-employment tax for Uber, Lyft, DoorDash, Instacart, Airbnb, Upwork, Fiverr. 72.5¢/mile mileage, SECA 15.3%, QBI 20%, OBBBA $2,000 1099-K threshold.
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