Full details in Main exemptions.
Some carriers may provide the driver with a card that can be shown to enforcement officers. The card will explain that carriage is under the terms of the derogation. This is useful because as long as the small load thresholds are not exceeded there is no requirement (on UK domestic journeys) for the vehicle to carry dangerous goods documentation. Some transfers are done by "paperless" systems so the driver may have no documentation at all.
Unless there are good reasons to take a different approach, enforcement officers are advised to accept the card as describing the situation outlined above. Where there is no card the driver may be able to describe the journey and the load and this will show that the relevant conditions are met.
Dutyholders should be able to show, when requested to do so by an HSE inspector: