CIL - Evidence to demonstrate an 'in-use building' - Public forum - Planning Advisory Service (PAS)

​​​​​​​Is anyone able to refer me to the relevant guidance on what types of evidence are admissible from a developer in order to demonstrate an 'in-use' building for the purposes of calculating a CIL liability?  (i.e. evidence that a building has been used for a continuous 6 month period up to the date of the planning permission).  Thank you