A mixed supply means a combination of two or more goods or services for a single price. Each of the goods or services can be supplied separately and is not dependent on any other. A mixed supply will have the tax rate of the good/service attracting the highest rate of tax.
For example, a gift box comprising sweets, chocolates, cakes, dry fruits, aerated drinks and fruit juices supplied for a single price is a mixed supply. Each of the goods mentioned above can also be sold separately. Since aerated drinks have the highest GST rate of 28%, aerated drinks will be treated as principal supply and 28% will apply on the entire gift box.