# International Standard Musical Work Code

Also known as: ISWC

> An International Standard Musical Work Code (ISWC) is the ISO 15707 identifier for a musical work: the composition, meaning its melody and any lyrics, independent of any recording. It is written as the letter T, nine digits and a check digit, for example T-123.456.789-C, and is usually assigned by a performing rights organization when the work is registered.

Source: https://wiki.snvrkotics.com/iswc · Category: Identifiers · Last reviewed: 2026-10-02 · License: CC BY 4.0

## Key facts

- **Standard:** ISO 15707
- **Format:** T, nine digits, one check digit
- **Identifies:** A musical work (composition)
- **International agency:** [CISAC](https://www.cisac.org/)
- **Usually assigned by:** [Performing rights organizations](https://wiki.snvrkotics.com/performing-rights-organization)
- **Recording counterpart:** [ISRC](https://wiki.snvrkotics.com/isrc)

## A work, not a recording

Music copyright distinguishes two things: the **musical work** written by songwriters and controlled by [publishers](https://wiki.snvrkotics.com/music-publishing), and the **sound recording** of a performance of it, the [master](https://wiki.snvrkotics.com/master-recording). The ISWC identifies the first; the [ISRC](https://wiki.snvrkotics.com/isrc) identifies the second. A song covered by ten artists has one ISWC and at least ten ISRCs.

## Format

An ISWC is the prefix letter **T** followed by a nine-digit work identifier and a single check digit, conventionally displayed as `T-123.456.789-C`. The dots and hyphens are for display only. The code carries no meaning beyond identity: it does not encode a country, a publisher or a year.[1]

## How an ISWC is assigned

The ISWC system is coordinated by CISAC, the International Confederation of Societies of Authors and Composers, through local agencies — in most countries the [performing rights organizations](https://wiki.snvrkotics.com/performing-rights-organization).[1][2] A code is usually issued when a work is first registered with a society, together with its writers, their shares and their interested-party identifiers. A work registered twice with conflicting writer shares is a common reason for a delayed ISWC, and for delayed royalties.

## In practice at SNVRKOTICS

In SNVRKOTICS a work and its recordings are separate records: the work carries the ISWC and the publishing split, each recording carries its own ISRC and master split, and the two are linked.

## Questions

### Do I need an ISWC to release a song?

No store requires one to accept a release, but publishing royalties are matched more reliably when the work has one, so registering the composition with a performing rights organization soon after release is good practice.

### What is the difference between an ISWC and an ISRC?

An ISWC identifies a composition; an ISRC identifies a specific recording of it. One ISWC can be linked to many ISRCs.

### Who gives out ISWCs?

Local ISWC agencies coordinated by CISAC — in practice usually the songwriter's performing rights organization, when the work is registered.

## References

1. CISAC. "ISWC International Agency." https://www.iswc.org/
2. CISAC. "International Confederation of Societies of Authors and Composers." https://www.cisac.org/

## Related

- [International Standard Recording Code](https://wiki.snvrkotics.com/isrc): The ISRC is a 12-character code, defined by ISO 3901, that identifies one specific sound recording or music video recording.
- [Music publishing](https://wiki.snvrkotics.com/music-publishing): Music publishing is the business of owning or administering song copyrights: registering works, licensing them and collecting songwriters' royalties.
- [Performing rights organization](https://wiki.snvrkotics.com/performing-rights-organization): A performing rights organization licenses the public performance of songs and pays the royalties to their songwriters and publishers.
- [Split sheet](https://wiki.snvrkotics.com/split-sheet): A split sheet is a signed record of who owns what percentage of a song or recording, agreed by every contributor and totaling 100%.

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Cite as: "International Standard Musical Work Code." SNVRKOTICS Wiki, 2026-10-02. https://wiki.snvrkotics.com/iswc