tax
Income Tax
Tax on personal income. For sole proprietors and pass-through entities, the main tax on business profit.
Definition
Income tax is the tax owed by individuals on personal earnings, including business profits passed through from sole proprietorships, single-member LLCs, S-Corps, and partnerships. In the US, federal income tax rates range from 10-37% depending on bracket, plus state income tax in most states. For owners of pass-through businesses, the business profit flows to their personal return. Tax planning - choice of entity, retirement contributions, timing of deductible expenses - can materially change the effective rate.
US federal income tax brackets and effective rates
Federal income tax in 2024 is graduated across 7 brackets: 10 percent up to about 11K single / 23K married filing jointly, then 12, 22, 24, 32, 35, and 37 percent. Brackets are marginal: only the income above each threshold is taxed at the higher rate. Effective rates (total tax divided by total income) are always lower than the top marginal rate. A US business owner with 200K taxable income pays roughly 33K federal income tax for an effective rate of 16.5 percent, despite being in the 24 percent marginal bracket. Add self-employment tax (15.3 percent on first 168K of net SE income, 2.9 percent above), state income tax (0 to 13 percent depending on state), and total tax burden on pass-through business income often lands at 35 to 45 percent for high earners.
Quarterly estimated taxes for self-employed
US self-employed individuals and pass-through business owners pay tax in four estimated installments: April 15, June 15, September 15, January 15 of the following year. The IRS safe harbor: pay either 100 percent of last year's tax (110 percent if last year's AGI exceeded 150K) or 90 percent of current year's tax through estimates. Underpayment triggers Form 2210 penalty calculated as IRS interest rate (currently 8 percent annualized) on the underpayment amount per quarter. Most US business owners use last-year safe harbor for simplicity. Tools: IRS Direct Pay, EFTPS, or have your CPA submit via tax software. Skipping or short-paying quarterly estimates produces unwelcome April surprises and penalty drag.
Entity choice and effective tax rate
US business owners materially change their tax bill through entity choice. Sole proprietor or single-member LLC (disregarded): all profit taxed as ordinary income plus full self-employment tax. S-Corp election: owner takes reasonable W-2 salary (subject to FICA) plus distributions (not subject to FICA), often saving 5 to 15K annually in payroll taxes for businesses earning 80K to 500K. C-Corp: 21 percent federal corporate tax plus double taxation on dividends; rarely optimal for small US businesses unless retaining substantial earnings or pursuing outside investment. Partnership / multi-member LLC: similar to sole proprietor but with K-1 distribution to partners. Revisit entity choice every 2 to 3 years; the optimal structure shifts as profitability grows.
Legitimate deductions that reduce US business income tax
Beyond ordinary business expenses, US business owners can reduce taxable income through several legitimate strategies. Retirement contributions: Solo 401(k) or SEP-IRA allows up to 69K (2024) tax-deferred contributions for self-employed. QBI deduction (Section 199A): up to 20 percent deduction on qualified business income for pass-through entities, with phase-outs above 191K single / 383K married. Health insurance: self-employed health insurance deduction on Schedule 1. Home office: actual expense or simplified method (5 dollars per sq ft up to 1500 sq ft). Vehicle: actual expense or standard mileage (67 cents per mile in 2024). Section 179 / bonus depreciation on equipment. Each has rules; document substantiation, and work with a CPA who specializes in business owners rather than W-2 employees.
FAQ
Should I elect S-Corp status for my LLC?
Generally yes once net business income reliably exceeds 50K to 80K annually. The S-Corp election lets you split income between W-2 salary (subject to FICA, 15.3 percent on first 168K) and distributions (not subject to FICA). The reasonable compensation rule requires you pay yourself a market-rate salary; the rest of profit can be distributed without payroll tax. Net savings typically 3K to 15K annually for businesses earning 80K to 500K. Below 50K net income, S-Corp overhead (payroll service, separate tax return, state franchise fees) usually exceeds the savings. Above 500K, the benefit caps because FICA caps.
What if I cannot pay my quarterly estimated tax?
Pay what you can, then catch up at the next quarterly or at filing. The penalty for underpayment is calculated as IRS interest rate (currently 8 percent annualized) on the shortfall per quarter - painful but not crippling. Worse: skipping payments entirely creates compounding penalty exposure plus state-level penalties. If you cannot pay April 15 estimates due to cash flow, file Form 4868 for extension (gives you to October 15 to file, not to pay) and pay what you can. The IRS offers installment plans (Form 9465) for outstanding balances over 50K.
How does the QBI deduction work for service businesses?
The Section 199A QBI (Qualified Business Income) deduction lets US pass-through business owners deduct up to 20 percent of qualified business income. For specified service trades or businesses (SSTBs) including consulting, law, accounting, financial services, health, athletics, and brokerage, the deduction phases out above 191K single / 383K married filing jointly (2024). Below the threshold: full 20 percent deduction. Above: partial deduction. Above the full phase-out: no deduction for SSTBs. Non-SSTB businesses can claim QBI even at higher incomes with wage and property limitations. The QBI deduction sunsets after 2025 unless Congress extends. Plan accordingly.
Can I deduct my home office?
Yes if you use part of your home regularly and exclusively as your principal place of business or for meeting clients. Two methods: simplified (5 dollars per square foot, max 1500 sq ft, total 7500 max) or actual expense (proportional share of mortgage interest, property tax, utilities, insurance, depreciation, repairs). Actual expense usually deducts more for larger or higher-cost homes but requires more documentation. For US S-Corp owners, the home office is reimbursed via an accountable plan (not deducted directly on the personal return); this nuance matters. W-2 employees lost the home office deduction in the TCJA - it remains for self-employed and business owners only.
What records should I keep for income tax?
IRS guidance: keep records substantiating income, deductions, and credits for at least 3 years from filing (the standard audit window), 6 years for substantial under-reporting (over 25 percent of gross income), and indefinitely for fraud or unfiled returns. Practical recommendation for US business owners: keep all bank statements, credit card statements, invoices, receipts (over 75 dollars), mileage logs, contracts, and tax returns for 7 years. Digital records via apps like Expensify, Dext, Hubdoc satisfy IRS requirements; you do not need paper. Store backups in two physical or cloud locations. Disorganized records turn audits from inconvenient to expensive.
In your business
- →Pay quarterly estimated taxes if you're self-employed - the IRS penalizes underpayment
- →Maximize legitimate deductions and retirement contributions before filing
- →Work with a CPA who specializes in business owners - generalist tax prep misses opportunities