The Same Salary in Four Countries

Comparable: the share of gross pay each system takes, at the same point in each country's own currency. That is a real fact about the four tax systems and it needs no exchange rate.

Not comparable: the cash amounts, because the same number of dollars, pounds and Singapore dollars is not the same money. Also not comparable: what the money buys. Rent in Singapore and rent in Adelaide are different problems, and tax is only one part of what leaves your account.

Also not in the picture: what the deductions buy you. British National Insurance and Australian Medicare levy fund healthcare that an American pays for separately, often through a premium deducted from the same payslip this calculator treats as untouched. A lower deduction rate is not automatically more money in hand.

Australia and Singapore start with a genuinely tax-free band — the first A$18,200 and the first S$20,000 are taxed at nothing — so low salaries keep almost everything. Singapore's schedule then climbs very gradually through thirteen bands, which keeps middle incomes light and only reaches 24% at the very top.

The United Kingdom looks moderate until £100,000, where the Personal Allowance is withdrawn at £1 for every £2 earned and the effective rate on that stretch jumps to 60%. The United States starts higher than the others at modest incomes, because FICA is charged from the first dollar with no tax-free band at all, and then flattens once the Social Security wage base is passed.