Have the inventory clerk walk you through the inventory write-down process and see that (s)he, authorises the write-down before making it.

Take a sample of documents that authorise inventory write-downs and check that they are all signed by the inventory controller.

For each form that authorises an inventory write-down, check that there are journal entries to adjust the inventory balance.

Take a sample of inventory write-downs from the inventory subledger and check that there is an authorisation form for each one.