VPDS031000 | Vaping Products Duty and Vaping Duty Stamps: What is a vaping product?: Legal definition
From HM Revenue & Customs · Vaping Products Duty and Vaping Duty Stamps guidance
A Vaping Product for the purposes of Vaping Products Duty is defined in section 116 of FA 26.
A vaping product is defined as being a liquid that either:
contains nicotine and either glycerine or glycol (or both)
is intended to be vaporised by a vape
It does not include medicinal products or tobacco products.
A liquid is still considered to be a vaping product even if the user must mix it with another liquid before consuming it in a vape device (for example, adding a nic shot to a shortfill).
A reference to a liquid also includes a liquid that has been frozen.