About OwnThatCheck
We built OwnThatCheck because the number on the offer letter and the money in your bank account are two very different things. Every calculator on this site answers the question that actually matters: what do you actually keep?
Our Mission
Most people negotiate salary without knowing what they'll actually take home. A $100,000 offer in California and a $100,000 offer in Texas produce meaningfully different bank deposits. A freelancer charging $80/hour as a 1099 contractor is not earning the same as an employee at $80/hour — they're paying an extra 15.3% in self-employment tax on top of income tax.
OwnThatCheck makes these numbers clear, immediate, and free. We don't charge for access, require registration, or store your financial data. Everything runs in your browser.
Calculation Methodology
Every number our calculators produce follows a documented methodology sourced from official government publications. Here is exactly how each major component is calculated:
Federal Income Tax
We apply the 2026 progressive federal tax brackets from IRS Revenue Procedure 2025-32. The standard deduction ($16,100 single / $32,200 MFJ) is subtracted from gross income before bracket application. Pre-tax deductions (401k, HSA) further reduce taxable income.
Source: IRS Revenue Procedure 2025-32
FICA (Social Security & Medicare)
Social Security: 6.2% on wages up to $184,500 (2026 wage base). Medicare: 1.45% on all wages with no cap. Additional Medicare Tax: 0.9% on wages above $200,000 ($250,000 MFJ). Employee share only — self-employed individuals pay double (15.3%) and deduct half.
Source: IRS Publication 15 (Circular E), 2026
State Income Tax
Each state's brackets, rates, and deductions are sourced from the respective state department of revenue. No-income-tax states (TX, FL, WA, NV, AK, SD, WY, NH, TN) correctly produce $0 state tax. Flat-rate states (IL, PA, etc.) use the confirmed 2026 flat rate. Progressive states use validated 2025-2026 bracket data.
Source: Individual state revenue departments
Self-Employment Tax
For 1099 and self-employed calculators, we apply the full 15.3% SE tax rate on 92.35% of net self-employment income (the IRS-approved reduction). The deduction of 50% of SE tax from gross income is applied before federal income tax calculation.
Source: IRS Schedule SE instructions, 2026
Bonus Tax Withholding
Flat method: 22% federal withholding on supplemental wages up to $1 million; 37% above $1 million. Aggregate method: bonus is added to most recent regular paycheck and withholding is calculated on the combined amount. State supplemental rates are applied where applicable.
Source: IRS Publication 15, Supplemental Wages
Official Data Sources
| Data Type | Source | Tax Year |
|---|---|---|
| Federal income tax brackets | IRS Revenue Procedure 2025-32 | 2026 |
| Standard deduction amounts | IRS Revenue Procedure 2025-32 | 2026 |
| Social Security wage base | Social Security Administration | 2026 |
| Medicare tax rates | IRS Publication 15 (Circular E) | 2026 |
| Self-employment tax rate | IRS Schedule SE | 2026 |
| Supplemental wage withholding | IRS Publication 15, Section 7 | 2026 |
| California income tax | CA Franchise Tax Board (ftb.ca.gov) | 2025-2026 |
| New York income tax | NY State Dept. of Taxation (tax.ny.gov) | 2025-2026 |
| All other state taxes | Individual state revenue departments | 2025-2026 |
Privacy & Data
All calculations run entirely in your browser using JavaScript. The salary, income, filing status, and deduction values you enter are never sent to our servers, stored in a database, or shared with third parties.
We use Google Analytics (via Google Tag Manager) to understand aggregate traffic patterns — page views, time on site, device types. This data is anonymized and does not include any of the financial values you enter into our calculators.
No account. No email. No credit card. No data collection of any financial inputs.
Frequently Asked Questions
How accurate are OwnThatCheck's calculators?
Our federal calculations use IRS Revenue Procedure 2025-32 directly. State calculations use official state revenue department data. Results are estimates — your actual withholding depends on your W-4 elections, additional income sources, and whether you itemize deductions. For tax filing, always consult a qualified tax professional.
Is OwnThatCheck free to use?
Yes, completely free. No account required, no email address needed. We will never charge for access to these calculators.
Does OwnThatCheck store my salary or tax information?
No. Everything runs in your browser. We do not transmit, store, or log any salary, income, or deduction values you enter.
How often is the tax data updated?
Federal data is updated annually when the IRS publishes the new Revenue Procedure (typically in October-November for the following tax year). State data is updated as states publish their annual rate schedules.
Why do my actual paychecks differ from the calculator?
The calculator estimates withholding using standard assumptions. Your actual paycheck depends on your W-4 withholding elections, employer payroll software, pay period timing, pre-tax benefits not entered into the calculator, and other factors. Use the calculator as a planning tool, not a guarantee.
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