Income Tax Calculator with Custom Brackets
How much of your salary do you actually keep after tax?
- Clear breakdown of every amount
- Handy for invoices and quotes
- Instant result, no sign-up
Income Tax Calculator with Custom Brackets
Enter your numbers and press Calculate
Worked examples across different systems
Because the calculator is universal, you just load the brackets of whichever system you care about. Here are three scenarios computed with the very formulas the tool runs.
- U.K. salary (£50,000). Personal allowance £12,570, bands of 20% (to £37,700), 40% (to £125,140) and 45%, plus 8% National Insurance. Taxable income is 50,000 − 12,570 = £37,430. Income tax comes to £7,486, contributions £4,000, total deductions £11,486 and net £38,514 — about £3,209.50 a month. The effective rate is 22.97% and the marginal rate 20%.
- High earner (£200,000, same bands). Now the 45% top band kicks in: income tax climbs to £70,546.50, the marginal rate is 45% but the effective rate is only 37.27%, because the first £37,700 of taxable income still pays just 20%.
- Flat 15% tax, no contributions ($60,000). Set both band limits to the income, all three rates to 15% and social contributions to 0%. The tool returns income tax of $9,000, an effective rate of 15% and a net of $51,000 — a quick way to model a flat-tax jurisdiction.
The recurring lesson: your effective rate is always lower than your marginal rate, because only the top slice of income pays the highest band.
The progressive tax formula, step by step
The calculation chains five steps. It first derives taxable income, then splits that base across the three bands and applies each rate, and finally produces the percentages.
base = max(0, gross − allowance)
band1 = min(base, limit1) × rate1
band2 = max(0, min(base, limit2) − limit1) × rate2
band3 = max(0, base − limit2) × rate3
tax = band1 + band2 + band3
contributions = gross × social_rate
net = gross − tax − contributions
effective rate = (tax + contributions) / gross × 100
where rates are divided by 100. The marginal rate is the band the last unit of the base falls into.
Worked example for £50,000 gross, £12,570 allowance, bands 20% / 40% / 45%, limits £37,700 and £125,140, and 8% contributions:
1. base = 50,000 − 12,570 = £37,430 2. band1 = min(37,430; 37,700) × 0.20 = 37,430 × 0.20 = £7,486 3. band2 = max(0; min(37,430; 125,140) − 37,700) × 0.40 = 0 4. band3 = max(0; 37,430 − 125,140) × 0.45 = 0 5. tax = 7,486 + 0 + 0 = £7,486 6. contributions = 50,000 × 0.08 = £4,000 7. net = 50,000 − 7,486 − 4,000 = £38,514 8. effective rate = 11,486 / 50,000 × 100 = 22.97%; marginal = 20% (the base sits in the first band). If a rate or allowance is zero, the matching term simply drops to zero — no special case needed.
Common mistakes and edge cases
- Confusing the effective rate with the marginal rate. The marginal rate is the band your last unit of income falls into; the effective rate is what you pay on average across all your income. The effective rate is almost always much lower — in the U.K. example, 22.97% versus a 20% or 40% marginal rate.
- Entering band limits out of order. Limit2 must be greater than limit1, and both are measured on the base after the allowance, not on the gross. If limit2 is below limit1 the middle band evaluates to zero and you understate the tax.
- Forgetting the allowance. Leave it at zero and your whole income is taxed from the first unit, inflating the tax. Always enter the tax-free slice your system grants.
- Adding contributions into the tax. Here tax and contributions are computed separately: tax on the taxable base, contributions on the gross. Total deductions add the two together.
- A 0% rate or allowance. Both are valid: a 0% band contributes nothing, and a 0% allowance makes all income taxable. There is no division by zero because the only divisions are by gross and by pay periods, both guarded.
- Mixing monthly income with annual brackets. Always enter the annual gross and let the tool divide by the pay periods; blending annual and monthly scales corrupts the result.
This calculator is for educational and informational purposes only: it is not tax advice or your authority's official figure. Real deductions, personal allowances and child or family reliefs can change the outcome — always confirm with your tax agency or an adviser.
About this calculator
This income tax calculator is built to be universal: you enter your own brackets and rates, so it works for the U.S., the U.K., Canada, Australia or any progressive system in the world. Type in your gross annual income, the tax-free allowance (the slice that is never taxed), the limits and rates of up to three progressive bands, and the percentage of social or payroll contributions withheld on your gross. The tool returns the income tax due band by band, the social contributions, total deductions, net annual income, take-home pay per pay period, your effective tax rate (the real share you pay on everything you earn) and your marginal rate (the rate on your last dollar earned). For example, on $50,000 gross with a $12,570 allowance and bands of 20%, 40% and 45%, the income tax comes to $7,486 and your effective rate is just 22.97% — far below the 20% headline that many people assume covers their whole income. This tool is for guidance only and does not replace your tax authority's official figures.
Frequently asked questions
What is the difference between effective and marginal rate?
The marginal rate is the percentage applied to the top slice of your income — what you would pay on each extra unit earned. The effective rate is total tax plus contributions divided by your gross income: the real share that leaves your pocket across everything you earn. Because the lower bands always tax at lower rates, the effective rate is almost always lower than the marginal. That is why a salary that reaches the 40% band rarely pays 40% on the whole amount.
Does this calculator work for my country?
Yes, because it ships with no fixed brackets for any country: you enter your own limits and rates. That is what makes it universal. Look up your tax authority's current bracket table, copy the allowance, the two limits and the three rates into the matching fields, and you get a calculation tailored to you. For systems with more than three bands, fold the top ones into the third rate; the result will be a good approximation of the upper end of the scale.
Why does it separate income tax from social contributions?
Because almost every system computes them on different bases. Income tax usually applies to taxable income (gross minus the allowance and other reliefs), while social contributions — Social Security, National Insurance, INSS — are charged on the gross, often with their own caps. Separating them shows how much each piece weighs and lets you adjust only the contribution percentage without touching the tax bands. Total deductions add both to give your real net.
Does the take-home per period include extra payments?
The take-home per period is simply the annual net divided by the number of pay periods you set. If your country pays 12 times a year, enter 12; if there are two extra payments as in Spain, enter 14 and you will see the split across fourteen equal instalments. The tool does not prorate extra payments in any special way: it spreads the total evenly, which is the clearest way to compare monthly take-home across scenarios. If your payslip prorates bonuses differently, adjust the number of periods to match your reality.
Can I use it for tax-free or very low income?
Yes. If your gross income is at or below the allowance, the taxable base is zero and the tax comes out as zero automatically, because the formula uses max(0, gross − allowance). In that case you will only see social contributions, if you entered a percentage, and the marginal rate shows as 0%. It is the perfect tool to check at what income level you actually start paying tax in your system: raise the gross until the tax stops being zero.