Omnia Fertilizer Limited, a fertilizer manufacturer, had claimed and been allowed deductions under s 11(a) of the Income Tax Act 58 of 1962 for expenditure on raw materials and transportation costs purchased on credit in tax years preceding 1991. When certain creditors failed to claim payment, the taxpayer allocated these unclaimed debts to income in tax years 1991-1994 (totaling R2,200,000 in 1991; R1,600,000 in 1992; R1,000,000 in 1993; and R1,935,000 in 1994). The taxpayer's practice was to debit an expenditure account and credit a 'received but not invoiced' account when materials were received. If no invoices were received, the taxpayer did not pay. After one year, half the unclaimed amounts were credited to income, and the other half after two years. The debts had not prescribed at any material time. The financial manager testified that based on experience, once amounts were written to income, it was highly improbable that invoices would be received, and indeed no creditor ever subsequently demanded payment.