Export subsidy assessment requires verification that tax rebates and drawback do not exceed charges on inputs consumed in exports. Export-linked tax remission, indirect-tax rebate and import-duty drawback may constitute export subsidies where relief exceeds taxes or charges on inputs consumed in producing exported goods. Consumed inputs include physically incorporated materials, energy, fuels, oil and consumed catalysts, with a normal allowance for waste. The designated authority examines whether the exporting government operates a reasonable and effective system to verify inputs and quantities; otherwise, actual inputs or transactions may require examination for excess payments. Substitution drawback is limited to equivalent domestic inputs replacing imported inputs and requires verification that no excess drawback occurs.