The binding legal principles established are: (1) For tax purposes, retrenchment costs are deductible in the year the expenditure is incurred, which is when an unconditional legal obligation arises - where Labour Act approval is required, this is when ministerial approval is granted, not when internal decisions are made or offers accepted; (2) The characterization of a transaction for tax purposes depends on its legal substance as evidenced by documentation and statutory compliance, not the labels parties apply to it; (3) Interest income is taxable to the party identified as lender in facility agreements who has the contractual right to receive such interest, regardless of subsequent payment instructions or agency claims not supported by contractual documentation; (4) Under section 30 and the 17th Schedule of the Income Tax Act, 'fees from a source within Zimbabwe' means fees where the originating cause is in Zimbabwe - the payer must be ordinarily resident in Zimbabwe and the fees must relate to services of a technical, managerial, administrative or consultative nature; (5) Bank charges levied by foreign banks on nostro accounts held for Zimbabwe-resident banks constitute fees for services of a managerial or administrative nature from a source within Zimbabwe, subject to withholding tax where the Zimbabwe bank (as payer) instructs transactions on behalf of Zimbabwe clients; (6) The definition of 'fees' in the 17th Schedule ('any amount') is broad and includes commissions and charges by whatever name called, save for express exclusions.