How to use the Indiana Paycheck Calculator

This Indiana Paycheck Calculator is a browser-based HTML + JavaScript tool that estimates an employee’s net pay per pay period by calculating federal withholding (estimated), FICA (Social Security and Medicare), Indiana state income tax (flat 2025 rate), optional county tax, and pre-tax deductions.

What the calculator does (short)

• Converts hourly or annual salary into gross pay for the selected pay period.
• Estimates federal income tax withholding using simplified 2025 tax-bracket math and the standard deduction.
• Computes Social Security (employee share) up to the 2025 wage base and Medicare (including additional Medicare tax where applicable).
• Applies Indiana’s flat state income tax rate used for withholding in 2025, and an optional county tax if you provide the county rate.
• Subtracts pre-tax deductions (e.g., 401(k) or HSA contributions per period) and shows estimated net pay.

Inputs explained

• Pay type: Choose Hourly (enter hourly rate and hours per period) or Salary (enter your annual salary).
• Pay period: Weekly (52), Biweekly (26), Semi-monthly (24), Monthly (12). The calculator uses these to annualize or de-annualize amounts.
• Filing status: Used only for estimating federal withholding (Single, Married filing jointly, or Head of household).
• Pre-tax deductions: Enter the total of your per-period pre-tax contributions (401(k), FSA/HSA withheld before tax).
• County tax rate: Indiana allows county income tax; if you know your county rate (decimal), enter it (for example, 0.0175 for 1.75%). If left blank or zero, no county tax is applied.
• Extra federal withholding: If you asked your employer to withhold an additional fixed dollar amount from each paycheck for federal tax, enter it here.

What the calculator shows

• Gross pay (per period) — what you earn before taxes/deductions for that paycheck.
• Federal tax (est.) — an estimate; for employer-accurate withholding, employers use IRS Publication 15-T / employer payroll software. The calculator uses progressive bracket math and the standard deduction to estimate federal tax, then divides it by pay frequency to produce per-period withholding. (See sources below.) 
• Social Security — employee portion (6.2%) up to the 2025 wage base ($176,100). This calculator prorates on an annualized basis.
• Medicare — base 1.45% on all wages + additional 0.9% above the $200,000 threshold (annualized).
• Indiana state tax — flat rate for 2025 (3.00% used in this calculator). The Indiana Department of Revenue notes the 2024 rate at 3.05% and that the rate adjusts to 3.00% in 2025. 
• County tax — if you supply a county rate it’s applied to taxable wages after pre-tax deductions.
• Net pay — estimated take-home pay per period after taxes & pre-tax deductions.

Key methodology notes (how numbers are computed)

• The calculator annualizes per-period gross pay to compute annualized federal tax and payroll taxes and then divides amounts back by the pay frequency. This provides a reasonable per-paycheck estimate for an employee who has no year-to-date tracking or multiple employers.
• Federal withholding is estimated using simplified progressive bracket math and a single standard deduction per filing status for 2025. This is an estimate — employer payroll systems commonly use IRS Publication 15-T tables or the wage-bracket method (which may produce slightly different per-period withholding). For exact withholding, consult the official IRS tables or your payroll department.
• Social Security withholding is capped at the SSA wage base for 2025; the calculator uses the announced 2025 wage base ($176,100) to limit the annual SS calculation.
• Medicare: the 1.45% base applies to all wages; the extra 0.9% additional Medicare tax is applied to annual wages above $200,000 (employer withholding rules require the employer to start withholding additional Medicare when wages exceed $200,000 in a calendar year regardless of filing status).

Example usage (step-by-step)

1. Open indiana-paycheck-calculator.html in a modern browser.
2. Select Hourly, Weekly, enter hourly rate 25 and hours 40. Leave county rate blank if you don’t know it.
3. Choose filing status Single, set pre-tax deductions (e.g., 50 for a $50 401(k) deduction per period), and press Calculate Net Pay.
4. The result panel shows gross, federal (estimate), Social Security, Medicare, state tax, and net pay per week.

Sources and authoritative references (important)

• Indiana Department of Revenue — income tax rates page (states 2024 = 3.05% and will adjust to 3.00% in 2025).
• Social Security Administration announcement / wage base info (2025 wage base). 
• IRS Publication 15-T / Publication 15 (withholding methods and tables) — used as the authoritative basis for federal withholding methodology. For precise employer withholding always use these IRS publications. 

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Disclaimer (expanded)

This tool is an estimate only and not an authoritative payroll or tax-preparation engine. It simplifies federal withholding (it uses representative 2025 brackets and a standard deduction), prorates Social Security and Medicare, and applies a flat Indiana state rate. It does not handle:

• Year-to-date wages, multiple-employer situations, or prior year-to-date withholding,
• Complex withholding scenarios (nonresident alien rules, supplemental wages special rules, multiple W-4 entries, credits, exemptions, or deductions beyond the standard deduction),
• Local withholdings other than a single county rate you enter,
• Employer-provided benefits that change taxability (some fringe benefits, pretax benefit rules vary),
• Payroll taxes for employer share, unemployment, or payroll tax deposits and reporting.

For official withholding, employers should use IRS Publication 15-T and state DOR withholding guidance. Consult a payroll professional or tax advisor for precise calculations, audit support, or tax planning.

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FAQ — Indiana Paycheck Calculator

Q: Is this calculator legally binding for payroll withholding?
A: No. This calculator provides estimates only. Official employer withholding must follow IRS Publication 15-T and state/local withholding rules.

Q: What Indiana state tax rate does the calculator use?
A: The calculator uses 3.00% as the Indiana flat tax rate for 2025 based on the Indiana DOR guidance that the 2024 rate (3.05%) will adjust to 3.00% in 2025. If official rates change you should update the constant in the code. 

Q: How exact is the federal withholding estimate?
A: It’s a reasonable approximation based on annualizing your wages, subtracting a standard deduction, and applying progressive 2025 bracket math. It does not replicate the IRS wage-bracket tables or the exact percentage-method worksheets used by payroll systems — for exact withholding use IRS Pub. 15-T or payroll software.

Q: How does the calculator treat Social Security and Medicare?
A: Social Security is calculated at 6.2% of wages up to the 2025 wage base (the calculator uses $176,100). Medicare is 1.45% on all wages, plus 0.9% additional Medicare on wages above $200,000 (annualized). Employer shares are not shown.

Q: Where do I find my Indiana county tax rate?
A: County income tax rates and codes are published by the Indiana DOR (county tax rate chart / PDF). You can enter the decimal equivalent (for example, 0.0175 for 1.75%). If you leave it blank the calculator only applies the state rate. 

Q: Can I change the tax rates used by the calculator?
A: Yes — the constants at the top of the JS (INDIANA_RATE_2025, SS_RATE, SS_WAGE_BASE_2025, etc.) can be edited to reflect later changes or your employer’s actual values.

Q: Does the calculator handle pretax retirement contributions or benefits?
A: The calculator subtracts a single pre-tax deduction amount per period (as you enter) before estimating state and local taxes. If you have multiple types of pretax items, sum them and enter the total. Complex pretax benefit rules (like employer pretax health premiums that interact with FICA or state rules) are not modeled precisely.

Q: My situation is complex (multiple jobs, recapture, nonresident). Should I rely on this tool?
A: No. For complex situations, use official forms, payroll software, or consult a tax/payroll professional. This calculator is best used for straightforward single-job estimates.