Under Personal Assessment, tax is calculated at progressive tax rates on the aggregated income of the individual (or of the couple, if married) from all sources. From this total income, business losses, approved charitable donations, interest payments on money borrowed for purpose of producing property income, personal allowances and concessionary deductions may be allowed. Tax is then charged on the balance at progressive tax rates similar to those used for Salaries Tax. As this method of computation of tax involves aggregating all chargeable income, tax is charged at marginal rate , and there is no separate taxation for married couples, it may not be advantageous for some taxpayers.