Safe harbour for diamond mining income permits electing a prescribed income determination method while limiting deductions and treaty recourse. A safe harbour permits eligible foreign diamond-mining companies to elect an agreed method for determining business income for tax purposes, subject to prescribed filing, limits on deductions and loss set-offs, adherence to defined definitions of raw diamonds and gross receipts, and transfer pricing obligations; the election may be invalidated by the assessing officer for incorrect or concealed facts and, if valid, precludes invoking mutual agreement procedures for that business.