The formula
How to calculate income tax
This calculator applies each country's own real progressive income tax brackets rather than a single flat rate. Pick a country from the dropdown and the whole calculation — the brackets, the currency, the rates — switches to match, whether that is the UK's HMRC bands, US federal brackets, or the equivalent scale for Ireland, Australia, Canada, New Zealand, Spain or Mexico. The underlying method is identical for every country; only the rate table and currency change, which is exactly what makes a single selector like this possible instead of needing a separate calculator per country.
Progressive tax does not apply one rate to your whole income. Instead, each bracket taxes only the slice of income that falls inside it: the first block at the lowest (often 0%) rate, the next block at the next rate, and so on up to whichever bracket your total income reaches. That is why the "marginal rate" — the rate on your last unit of income earned — is always higher than the "effective rate", which is the average rate across all of your income.
What to enter:
- Annual income — gross, before any tax or deductions, in the selected country's own currency
- Country
No submit button: type and the answer moves. Your inputs end up in the link, so the page can be shared already filled in.
The order the fields are filled in makes no difference to the result — the calculator recomputes the whole formula from whatever is currently in every field, not step by step. That means it is safe to adjust one number, watch the result change, and adjust it back, without worrying about resetting anything first.
Why income tax matters
Most people who look up a income tax calculation already have a specific number in mind — a quote, an offer, a target — and want to check it rather than learn the theory behind it. This page is built for that: enter your own figures, see the result immediately, and change any field to see how the answer moves without redoing the arithmetic from scratch each time.
Beyond a one-off check, the same calculation is worth revisiting whenever the underlying numbers change — a new interest rate, a change in income, a different term. Because the figures live in the page's own web address, coming back to update just one field and compare the new result against the old one takes seconds rather than starting again from a blank page.
This kind of calculation rarely stands entirely alone. A income tax figure usually feeds into a wider decision — how it compares with a competing offer, whether it fits inside a monthly budget, what it does to a longer-term plan — and the value of having it as an exact number rather than a rough guess is that those follow-on comparisons stop being guesswork too. Once one figure in a decision is precise, it is worth making the effort to get the others precise as well, rather than mixing an exact calculation with several estimates and treating the result as equally reliable.
A calculator like this one is often bookmarked and returned to repeatedly over months rather than used once, particularly for anything tied to an ongoing plan such as a mortgage, a savings goal or an investment being tracked. Because the figures live in the web address rather than only in memory, coming back to the same page with updated numbers is quicker than starting from a blank spreadsheet each time.
Worked example
Take the figures the calculator starts with:
- Annual income: 30,000
- Country: GB
That gives:
- Income tax owed: 3,486 £
- Net income after tax: 26,514 £
- Effective tax rate: 11.62 %
- Top marginal rate applied: 20 %
These figures are only the calculator's own starting values, included so the working is visible rather than hidden inside the tool above. Replace them with your own numbers and the same arithmetic applies — nothing about the method changes, only the inputs feeding it.
Reading the result
The effective rate is almost always well below the marginal rate, because only the top slice of income is taxed at that top rate — everything below it is still taxed at the lower brackets it passed through. A large gap between the two figures is normal and does not mean an error; it is exactly how progressive taxation is designed to work, in every country this calculator covers.
Where this goes wrong. The most common mistake is applying the top bracket's rate to the entire income, which overstates the tax owed substantially. A second is comparing two countries' figures directly without accounting for the currency difference — the same numeral means very different things in pounds, dollars, euros or pesos, and none of the figures convert to each other without an exchange rate.
A useful check on any unfamiliar result is to compare it against a rough mental estimate first — round the inputs to convenient numbers and see whether the calculator's answer lands in roughly the same territory. A wildly different figure usually means one of the fields was entered in the wrong unit, most often a percentage typed as a whole number where a decimal was expected, or the reverse.
No. Spain's IRPF splits between a national scale and a regional scale set by each autonomous community, and this calculator uses the national scale only as a representative approximation. Mexico's ISR shown here is the federal annual schedule for individuals. Treat the result as a solid estimate, not a final filing figure.
No, and this varies a lot by country — worth checking carefully before relying on a number. The UK figure is HMRC's England/Wales/Northern Ireland bands (Scotland uses different bands). The US figure is federal tax only for a single filer; most states add their own income tax on top, and a few charge none. Canada's figure is federal tax only; provincial tax is separate and typically larger. Australia's figure excludes the 2% Medicare levy. Ireland and Canada both also apply personal tax credits after the rate calculation, which further reduce the real bill below what the raw bands here show. Spain's IRPF splits between a national scale and a regional scale set by each autonomous community; this calculator uses the national scale only. Treat every result as a solid estimate, not a final filing figure.
Yes — the calculator is built so that adding another country is a matter of adding another bracket table and currency, not building a new page. The countries listed are the first batch; the same selector pattern is designed to extend to more.
The answer it gives you is income tax owed. With 30,000 annual income, that comes to 3,486 £. Change any field and the figure moves with it.
Whenever one of the underlying figures changes — a new interest rate, a different balance, an updated term — since the result only reflects what is currently in the fields. There is no need to keep a separate record of past results; the web address for a filled-in version already carries the figures used to produce it.
Not unless a tax rate or a fee is explicitly one of the inputs above. Where it is not, the figure shown is a gross calculation, and any tax due depends on your personal circumstances and current tax rules, which are worth checking separately.
The arithmetic itself is exact — the calculator applies the formula shown above precisely, with no rounding until the final figure is displayed. The uncertainty, where it exists, is entirely in the inputs: an estimated rate or an approximate balance carries that same approximation through to the result.
Example by country
The same income of 30,000, read in each country's own currency, shows how differently the same numeral behaves once it is run through a different bracket table:
| Country | Tax owed | Net income | Effective rate | Marginal rate |
|---|---|---|---|---|
| 🇬🇧 UK | £3,486.00 | £26,514.00 | 11.62% | 20% |
| 🇺🇸 US (federal) | $1,420.00 | $28,580.00 | 4.73% | 12% |
| 🇮🇪 Ireland | €6,000.00 | €24,000.00 | 20% | 20% |
| 🇦🇺 Australia | A$1,770.00 | A$28,230.00 | 5.9% | 15% |
| 🇨🇦 Canada (federal) | C$4,200.00 | C$25,800.00 | 14% | 14% |
| 🇳🇿 New Zealand | NZ$4,158.00 | NZ$25,842.00 | 13.86% | 17.5% |
| 🇪🇸 Spain | €7,165.50 | €22,834.50 | 23.89% | 30% |
| 🇲🇽 Mexico | MX$1,518.93 | MX$28,481.07 | 5.06% | 6.4% |
None of these figures are directly comparable to each other — 30,000 pounds, dollars, euros and pesos represent very different amounts of real purchasing power, and the table exists to show how the bracket structure itself differs, not to rank the countries. New Zealand starts taxing from the first dollar with no exemption band, while the UK, US and Australia exempt an initial slice entirely; Ireland and Canada apply the rate bands shown here before a further personal tax credit reduces the bill, so their real-world figures run a little lower than shown. Enter your own income and country in the calculator above for a figure that reflects your own currency and situation.