Comprehensive tax calculator
https://www.ato.gov.au/calculators-and-tools/comprehensive-tax-calculator/

Exchange Rates
https://www.ato.gov.au/rates/foreign-exchange-rates/

For individuals
https://www.ato.gov.au/Individuals/

For businesses
https://www.ato.gov.au/Business/

Income Tax Rates
https://www.ato.gov.au/individuals/income-and-deductions/how-much-income-tax-you-pay/individual-income-tax-rates/

Key dates for business
https://www.ato.gov.au/Business/Yearly-reports-and-returns/Due-dates-for-the-current-financial-year/

Tax withheld calculator
https://www.ato.gov.au/Calculators-and-tools/Tax-withheld-calculator/Individual-Non-business-Calculator.aspx