COMPOSITE SUPPLY
Section 2 (30) - " Composite supply" means a supply made by a taxable person to a recipient consisting of two or more taxable supplies of goods or services or both, or any combination thereof, which are naturally bundled and supplied in conjunction with each other in the ordinary course of business, one of which is a principal supply.
Illustration. - Where goods are packed and transported with insurance, the supply of goods, packing materials, transport and insurance is a composite supply and supply of goods is a principal supply.
Section 2 (90). - " principal supply" means the supply of goods or services which constitutes the predominant element of a composite supply and to which any other supply forming part of that composite supply is ancillary.
Mixed Supply
Section 2 (74) " Mixed supply" means two or more individual supplies of goods or services, or any combination thereof, made in conjunction with each other by a taxable person for a single price where such supply does not constitute a composite supply.
Illustration. -- A supply of a package consisting of canned foods, sweets, chocolates, cakes, dry fruits, aerated drinks and fruit juices when supplied for a single price is a mixed supply. Each of these items can be supplied separately and is not dependent on any other. It shall not be a mixed supply if these items are supplied separately.
Tax Liability 
Section 8 - The tax liability on a composite or a mixed supply shall be determined in the following manner; namely: -
(a) a composite supply comprising two or more supplies, one of which is a principal supply, shall be treated as a supply of such principal supply; and
(b) a mixed supply comprising two or more supplies shall be treated as a supply of that particular supply which attracts the highest rate of tax.
Composite or Mixed Supply - Issues
Schedule II - Activities to be treated as supply of goods or supply of services
Composite supply
The following composite supplies shall be treated as a supply of services, namely- (a) works contract as defined in clause (119) of section 2; and (b) supply, by way of or as part of any service or in any other manner whatsoever, of goods, being food or any other article for human consumption or any drink (other than alcoholic liquor for human consumption), where such supply of service is for cash, deferred payment or other valuable consideration.
Flyer on Composite and Mixed Supply - 
A work contract and restaurant services are classic examples of composite supplies, however the CGST Act (Schedule II - SI No. 6)
identifies both as supply of services and chargeable to specific rate of tax mentioned against such services (works contract and restaurants)
AMC Contract:
(a) Spares @ 12% and Repair Services @ 18%
(b) Spares @ 28% and Repair Services @ 18%
(c) Spares @ 28% & 18% and Repair services @ 18%
GST Tariff Schedule
Explanation (iii) to the notification -
Tariff item, sub-heading, heading and chapter shall mean respectively a tariff items, sub-heading and chapter as specified in the First Schedule to the customs Tariff Act, 1975
Explanation (iv) to the notification - 
The rules for the interpretation of the First Schedule to the Customs Tariff Act, 1975 including the Section and chapter Notes and the General Explanatory Notes of the First Schedule shall, so far as may be, apply to the interpretation of this notification
General Rules of Interpretation
Rule 1 - > The titles of Sections, Chapters and Sub-Chapters are provided for ease of reference only.
>for legal purposes, classification shall be determined according to the terms of the leadings and any relative Section or chapter Notes and,
> provided such headings or Notes do not otherwise require, according to the following provisions:
Rule 2 (a) - > Any reference in a heading to an article shall be taken to include a reference to that article incomplete or unfinished, provided that, as presented, the incomplete or unfinished article has the essential character of the complect or finished article.
> It shall also be taken to include a reference to that article complete or finished (or failing to be classified as complete or finished by virtue of this rule) presented unassembled or dis-assembled.
Rule 2 (b)- > Any reference in a heading to a material or substance shall be taken to include a reference to mixtures or combinations of that material or substance with other materials or substances.
> Any reference to goods of a given material or substance shall be taken to include a reference to goods consisting wholly or partly of such material or substance
> The classification of goods consisting of more than one material or substance shall be according to the principles or rule 3.
General Rules of Interpretation
Rule -3 When by application of Rule 2(b) or for any other reason, goods are, prima facie, classifiable under two or more headings, classification shall be affected as follows:
Rule 3 (a) > The heading which provides the most specific description shall be preferred to headings providing a more general description.
> However, when two or more headings each refer to part only of the materials or substances contained in mixed or composite goods or the part only of the items in a set put up for retail sale, those headings are to be regarded as equally specific in relation to those goods, even if one of them gives a more complete or precise description of the goods.
Rule 3 (b) Mixtures, composite goods consisting of different material or made up of different components, and goods put up in sets for retail sale, which cannot be classified by reference to 3 (a), shall be classified as if they consisted of the material or component which gives them their essential character, insofar as this criterion is applicable
Rule 3 (C) When goods cannot be classified by
reference to 3 (a) or 3(b), they shall be classified under the heading which occurs last in numerical order among those which equally merit consideration.
Goods imported in sets > During import of goods imported in sets - General Rules of Interpretation of the customs Tariff Act will apply
> Such goods cleared as such in domestic market - Whether provisions of: Composite or Mixed supply will be attracted? OR whether General Rules for Interpretation of the customs Tariff Act, 1975 will prevail over CGST Act?
