How does the payroll withholding relief work?

Taxpayers who export at least 85% of the FOB value of the goods they manufacture have the income tax calculated on the wages of their production staff deferred, and cancelled once the condition is met. The ratio is measured annually, so if the export share falls below 85% during the year the relief is lost for that year. The condition is a threshold, not a sliding scale, and falling below it produces a total loss rather than a partial one.