What Is an ISWC?
The International Standard Musical Work Code uniquely identifies a musical composition — the song itself, independent of any recording.
Look up any ISWC — Search musical works by ISWC code, song title, or songwriter name using our free database.
Search ISWCsWhat is an ISWC code?
An ISWC (International Standard Musical Work Code) is a unique identifier assigned to a musical composition. While an ISRC identifies a specific recording, an ISWC identifies the underlying work — the melody, lyrics, and arrangement that make up the song.
ISWCs are defined by the international standard ISO 15707 and are managed by CISAC (the International Confederation of Societies of Authors and Composers). They are essential for tracking mechanical and performance royalties owed to songwriters and publishers.
ISWC format and structure
Every ISWC follows a fixed format:
Prefix — Always the letter "T", indicating this is a musical work code
Work ID — Nine-digit unique identifier for the musical work
Check Digit — Single digit used to validate the code's accuracy
How ISWCs relate to ISRCs
The relationship between ISWCs and ISRCs is one-to-many. A single musical work (ISWC) can have many recordings (ISRCs):
Musical Work (ISWC)
"Yesterday" by Lennon/McCartney
Recording 1 (ISRC) — The Beatles, 1965 studio version
Recording 2 (ISRC) — The Beatles, 1966 live version
Recording 3 (ISRC) — Cover by Frank Sinatra
Recording 4 (ISRC) — Cover by Boyz II Men
This is why ISWCs are critical for songwriters — they ensure royalties from every version of a song are attributed to the correct composition.
Why are ISWCs important?
- Mechanical royalties — The MLC (Mechanical Licensing Collective) and international CMOs use ISWCs to match recordings to works and distribute mechanical royalties to songwriters and publishers.
- Performance royalties — PROs use ISWCs to track when songs are performed publicly (radio, live, streaming) and pay the appropriate rights holders.
- Sync licensing — When a song is licensed for use in film, TV, or advertising, ISWCs help identify the correct composition and its rights holders.
- Cross-border royalty distribution — ISWCs enable international societies to identify and exchange royalty information for the same work across territories.
How to get an ISWC
ISWCs are assigned through performing rights organizations:
- Register your works with a PRO — If you are a songwriter, register your compositions with ASCAP, BMI, SESAC (US), PRS (UK), SACEM (France), or your local society.
- ISWC assignment is automatic — Once registered, your PRO will submit the work to the ISWC system, and an ISWC will be assigned automatically.
- Verify via CISAC or your PRO — You can check if your work has been assigned an ISWC through your society's online portal or by searching on iswc.fm.
Frequently asked questions
What does ISWC stand for?
ISWC stands for International Standard Musical Work Code. It is a unique identifier for musical compositions — the underlying song, as distinct from any specific recording of that song.
What is the difference between ISRC and ISWC?
An ISRC identifies a specific recording (the audio file), while an ISWC identifies the underlying musical composition (the song itself). One ISWC can have many ISRCs — for example, the original recording, a live version, and a cover all share the same ISWC but have different ISRCs.
How do I find the ISWC for a song?
You can look up an ISWC using the free search tool at iswc.fm or credits.fm. You can search by ISWC code, song title, or songwriter name. ISWCs are also available through CISAC and national performing rights organizations.
Who assigns ISWC codes?
ISWCs are assigned by authorized ISWC agencies, typically through performing rights organizations (PROs) like ASCAP, BMI, and SESAC in the United States, PRS in the UK, and SACEM in France. The global ISWC system is managed by CISAC.
Can a song have multiple ISWCs?
In theory, each unique musical work should have exactly one ISWC. However, in practice, duplicate ISWCs can exist due to separate registrations in different territories. The industry works to merge these duplicates over time.
Do I need an ISWC to release music?
No. Unlike ISRCs, ISWCs are not required for digital distribution. However, having an ISWC registered with your PRO ensures proper royalty tracking for mechanical and performance royalties, especially for songwriters and publishers.
Related guides: What Is an ISRC? · What Is an IPI?