Small business tax research
Longer-form analysis behind the calculators, the rules, rates, and edge cases that decide what self-employed people and small businesses actually owe, grounded in IRS and state sources.
What can you learn from SmallBizCalc research?
Research scope · August 2026
SmallBizCalc research explains estimated-tax and state-rate rules beside a 51-jurisdiction SOS LLC fee table (median first-year composite $310; 2 require publication) - answering one filing, SECA, or state-tax question per study.
Counts from the SmallBizCalc Secretary of State LLC fee table (August 2026). Registry facts only; not formation or tax advice. How we calculate →
Quarterly Estimated Tax Payments: Avoiding Underpayment Penalties
Underpayment penalties, safe-harbor thresholds, and optimal quarterly payment strategy for the self-employed.
Read analysis →Self-Employment Tax: A Complete Calculation Guide
How SECA works, the 15.3% rate, the deductible employer-half, the wage base, and ways to reduce the bill.
Read analysis →Small Business Tax Rates by State: A 50-State Comparison
Corporate rates, pass-through treatment, franchise and gross-receipts taxes compared across all 50 states.
Read analysis →Download the SOS LLC first-year fee extract cited on this page: llc-first-year-fees.csv (CC0). Method notes live on /statistics and /methodology.