VATREC17024 - Particular invoices with special arrangements: Returnable containers: Containers for which no separate charge is made
If containers are not separately charged for, either when they are sent out or subsequently, no separate charge of VAT is required. This applies even if the supplier normally expects the containers to be returned but they are not returned in a particular instance. (But see paragraph 8.2 of VAT guide (VAT Notice 700) - GOV.UK about containers that constitute more than ‘normal or necessary’ packaging).