The items that actually go missing
Keys are the obvious one, and the safest assumption is that not all copies will come back. A lock or code change at handover costs less than the uncertainty of not knowing how many keys exist. Alarm codes should be reissued rather than transferred. Access passes should be deactivated on the last day of the outgoing service rather than at some point afterwards when someone remembers.
Consumable stock and client-owned equipment are the quieter losses. Stock held on site may have been supplied by the outgoing contractor and will leave with them, so a building that assumed it was covered finds itself empty on the first morning. Recording what is on site, who owns it and what will remain avoids a first week spent chasing hand towel.
