Amortisation of mineral development expenditure allows ten-year deductions, subject to eligibility, audit, carry-forward, and exclusion rules. Amortisation of expenditure for development of certain minerals is available to an eligible assessee engaged in prospecting, extraction or production of minerals, with the qualifying expenditure generally deducted in ten equal instalments. The deduction is limited to the income from commercial exploitation of the mine or mineral deposit, and unabsorbed instalments may be carried forward only up to the tenth tax year. Exclusions include acquisition of the mineral source site and capital items eligible for depreciation, while audit, prescribed reporting, and special rules for amalgamation or demerger apply.