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
HSA & FSA Tax Savings Calculator
Calculate federal + state + FICA tax savings from HSA and FSA contributions. 2026 HSA $4,400/$8,750, Health FSA $3,400, Dependent Care $5,000.
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Taxes
529 College Savings Tax Calculator
Calculate 529 plan tax benefits: state deductions/credits (NY $10K, IL $20K, IN 20%), federal tax-free growth, OBBBA $20K K-12, $35K Roth IRA rollover, superfund.
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Taxes
1099-NEC Business Tax Calculator
Calculate 1099-NEC issuance, backup withholding, and recipient self-employment tax. NEW OBBBA $2,000 threshold (was $600), 24% backup withholding, SECA 15.3%, QBI 20%.
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Taxes
Stock Capital Gains Tax Calculator
Calculate federal + state tax on stock sales: 0/15/20% LTCG, ordinary STCG, NIIT 3.8%, QSBS $15M exclusion (OBBBA), wash sale rule, capital loss carryover.
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Taxes
Options Trading Tax Calculator
Calculate federal tax on options trades. Equity options (regular cap gains), §1256 contracts (60/40 mark-to-market, no wash sale), broad-based index options (SPX, NDX), Form 6781.
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Taxes
Land Sale Capital Gains Tax Calculator
Calculate federal + state tax on raw land sales: 0/15/20% LTCG, 1031 like-kind exchange deferral, dealer/inventory rules, NIIT 3.8%, basis adjustments for taxes and improvements.
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Taxes
LLC vs S-Corp Tax Comparison Calculator
Compare total federal tax under LLC/Sole Prop vs S-Corp election. Saves SE tax via reasonable salary + distributions split. 2026 SS $184,500 wage base, QBI 20%, payroll overhead.
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Taxes
Child & Dependent Care Credit Calculator
Calculate the federal Child & Dependent Care Credit. NEW OBBBA 2026: max 50% rate (was 35%), phase down to 20% by $103K/$206K AGI. Combine with Dependent Care FSA.
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Taxes
Estate & Trust Tax Calculator
Calculate trust income tax on Form 1041 with the brutally compressed 2026 brackets (37% kicks in at $16K!), distribute DNI to beneficiaries, NIIT 3.8%, grantor trust pass-through.
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Taxes
Small Business Deduction Calculator
Stack the 5 major small business tax deductions: §199A QBI 20%, §174A R&E immediate expense, §168(k) 100% bonus depreciation, §179 $1.25M, §163(j) interest limit.
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