Question 1

How is US federal income tax calculated?

Accepted Answer

US federal income tax uses a progressive tax system with seven brackets for 2025: 10%, 12%, 22%, 24%, 32%, 35%, and 37%. Each bracket applies to income within specific ranges that vary by filing status. You only pay the higher rate on income above each threshold, not your entire income.

Question 2

How much tax do I pay on $100,000 salary?

Accepted Answer

On a $100,000 salary in 2025, a single filer pays approximately $17,400 in federal tax, $7,650 in FICA taxes, plus state tax (varies by state). In a no-income-tax state, your take-home pay would be around $74,950. In California, it would be closer to $68,500 after state tax.

Question 3

What are FICA taxes?

Accepted Answer

FICA (Federal Insurance Contributions Act) taxes fund Social Security and Medicare. Employees pay 6.2% for Social Security on income up to $176,100 (2025 limit) and 1.45% for Medicare on all income. High earners pay an additional 0.9% Medicare tax on income over $200,000 (single) or $250,000 (married filing jointly).

Question 4

Which states have no income tax?

Accepted Answer

Nine states have no state income tax: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, and Wyoming. This can significantly increase your take-home pay compared to high-tax states like California or New York.

Question 5

What is the standard deduction for 2025?

Accepted Answer

For 2025, the standard deduction is $15,000 for single filers, $30,000 for married filing jointly, and $22,500 for heads of household. These amounts are subtracted from your gross income before calculating tax. Most taxpayers benefit more from the standard deduction than itemizing.

Question 6

How does 401(k) contribution affect my paycheck?

Accepted Answer

Traditional 401(k) contributions are pre-tax, meaning they reduce your taxable income. This lowers your federal and state income tax, though you still pay FICA taxes on the full amount. For 2025, you can contribute up to $23,500 ($31,000 if age 50 or older). Many employers offer matching contributions.

Question 7

What is my effective tax rate vs marginal tax rate?

Accepted Answer

Your marginal tax rate is the rate on your last dollar of income (your tax bracket). Your effective tax rate is your total tax divided by total income. For example, earning $100,000 puts you in the 22% bracket (marginal), but your effective rate is around 17% because lower portions are taxed at lower rates.

Question 8

How much should I withhold on my W-4?

Accepted Answer

Your W-4 withholding depends on your filing status, income, deductions, and whether you have multiple jobs. The IRS Tax Withholding Estimator can help. Aim to neither owe significantly nor receive a large refund—a refund means you gave the IRS an interest-free loan.

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