GST on auxiliary boiler plant remains applicable under Schedule provisions until the specified date, continuing under existing classification. Auxiliary plant for use with boilers under the relevant boiler headings (for example, economisers, super-heaters, soot removers, gas recoverers) and condensers for steam or other vapour power units are classified as goods under Schedule 3 and attract GST at 18%, with that rate and schedule applicability recorded as operative until the specified cutoff date in the notification.