ISWC vs ISRC is one of the most confusing topics in music registration, because the two codes look similar and even sound alike. But they identify two completely different things, and mixing them up can cost you royalties. If you are asking "what is an ISWC," the short answer is: it is the ID for your song (the composition), while the ISRC is the ID for your recording. This guide explains both, who assigns them, where each one goes, and how covers and remixes work.
One song, two assets: composition vs recording
Every time you release music, you create two separate copyrighted assets:
- The composition. The melody and lyrics. Owned by the songwriters and their publishers.
- The sound recording (the master). A specific recorded performance of that composition. Owned by whoever owns the master, often the artist or label.
Each asset needs its own ID so the music industry can track it:
- The ISWC identifies the composition.
- The ISRC identifies the recording.
A simple way to remember
- ISWC has a C for composition.
- ISRC has an R for recording.
That is not the official meaning of the letters, but it is an easy memory trick. Officially, ISWC stands for International Standard Musical Work Code, and ISRC stands for International Standard Recording Code.
Why two assets means two sets of royalties
Composition royalties come from your PRO and The MLC. Recording royalties come from your distributor and SoundExchange. That is why we say you own 200%. See both sides on the Royalty Map.
What an ISWC identifies and who assigns it (your PRO)
The ISWC is a unique identifier for a musical work: the song itself, regardless of who performs or records it.
What it looks like
An ISWC typically starts with the letter T, followed by nine digits and a check digit, often shown like T-123.456.789-0.
Who assigns it
ISWCs are issued through the international ISWC system, and songwriters usually get them through registration with their collecting society. In the US, when you register a song with your PRO, an ISWC is commonly assigned to that work. It may take some time to appear after you register.
You generally do not apply for an ISWC separately. Registering your song with your PRO is the usual path. Check your PRO's member portal, such as BMI or ASCAP, for the ISWC on each registered work.
One composition, one ISWC
A song has one ISWC, no matter how many times it is recorded. The original version, a live version, a remix, and a cover by another artist all share the same composition, so they share the same ISWC.
What an ISRC identifies and who assigns it (your distributor)
The ISRC is a unique identifier for one specific recording.
What it looks like
An ISRC has 12 characters: a country code, a registrant code, a year, and a designation number, often shown like US-AB1-26-00001.
Who assigns it
Most independent artists get ISRCs from their distributor when they upload a release. Some artists and labels obtain their own registrant code and issue ISRCs themselves.
We cover this in detail in what an ISRC code is and how to get one.
One recording, one ISRC
Each distinct recording gets its own ISRC. A remix, an acoustic version, and a radio edit each need their own. The same recording, rereleased on an album, keeps its original ISRC.
Why mixing them up loses royalties
Codes are how computers match money to owners. When the wrong code is in the wrong place, the match can fail.
Putting an ISRC where an ISWC belongs
If a form asks for the ISWC of your composition and you enter an ISRC, the organization may not be able to link your song to the right work. Composition royalties could go unmatched.
Putting an ISWC where an ISRC belongs
If you give a recording registration an ISWC instead of the ISRC, plays of that recording may not connect to your registration.
Linking the right codes together
Many registrations let you connect both codes. For example, when you register a composition at The MLC, you can add the ISRCs of recordings of that song. That link tells the system "these recordings use this composition," which helps route mechanical royalties correctly.
Duplicate codes
Two ISRCs for the same recording, or two registrations for the same composition, split your data and can leave money unmatched. Keep one code per asset and reuse it everywhere.
If you suspect money has already slipped through, run the free Missed Royalties Check.
Where each code goes in your registrations
Here is a simple map.
Your PRO
- ISWC: Assigned to your registered work. Save it once it appears.
- ISRC: Some PRO forms let you add recording information, including ISRCs, which can help match performances.
The MLC
- Composition registration: Writers, shares, IPIs, and the ISWC if you have it.
- ISRCs: Add the ISRC of every recording of the song so streams match your work. According to The MLC, recording data helps with matching. Our MLC registration guide walks through it.
SoundExchange
- ISRC: Required to identify your recordings. SoundExchange pays on recordings, not compositions, so the ISWC is not the key here. See our SoundExchange registration guide.
Your distributor
- ISRC: Assigned or entered per track.
- UPC: Assigned per release.
- ISWC: Some distributors ask for songwriter and publishing details; include accurate writer info.
Copyright Office
The Copyright Office does not require ISWCs or ISRCs to register, but keep your titles and authors consistent with your other registrations.
Chart and data services
Services like Luminate track recordings using ISRCs and releases using UPCs.
How covers and remixes work (same ISWC, new ISRC)
This is where the two codes really show their purpose.
Covers
When another artist records a cover of your song:
- The composition is the same, so it keeps the same ISWC.
- The recording is new, so it gets a new ISRC, issued by the cover artist's distributor or label.
That means you, as the songwriter, still earn composition royalties from the cover, as long as the recording is linked to your work. This is one reason registering your composition with correct data matters so much.
Remixes
When you or someone else remixes your recording:
- The composition is usually still the same song, so it keeps the same ISWC, unless the remix adds new writing that changes the composition. If new writers contribute new music or lyrics, you may need to treat it as a new work and update your split sheet.
- The recording is new, so it gets a new ISRC.
Live versions, acoustic versions, and edits
Same idea. Same composition, same ISWC. New recording, new ISRC.
When you cover someone else
If you record a cover, the ISWC belongs to the original songwriters. You need a mechanical license to distribute it, and your distributor may help with that. Your recording gets its own ISRC.
Keep a catalog sheet
For each song, track:
- Song title and ISWC
- Writers and splits (see our split sheet guide)
- Every recording of that song, each with its own ISRC and version name
- The UPC of each release
Royalty Lock keeps this sheet for you. You enter your song and recording details once, and the AI puts the right code in the right place in every file and form it preps. You submit under your own login. See How it works, or start with the pillar guide on how to register a song everywhere it earns.
Quick comparison
| ISWC | ISRC | |
|---|---|---|
| Identifies | The composition (song) | One recording |
| Typical source | Through your PRO or society | Your distributor or your own registrant code |
| How many per song | One | One per recording or version |
| Used by | PROs, The MLC, publishers | Distributors, SoundExchange, The MLC, chart services |
| Covers | Same ISWC | New ISRC |
A real world example
Say you write a song called "Paper Moon" with one co-writer. Here is how the codes play out over time.
- You register the composition with your PRO, listing both writers and a 50/50 split. Some time later, an ISWC appears on the work in your PRO portal. You save it.
- You release your studio version through a distributor. The distributor assigns ISRC #1. You save it along with the single's UPC.
- You register the work at The MLC with both writers, both IPIs, the ISWC, and ISRC #1.
- You register the recording at SoundExchange using ISRC #1.
- A year later you release an acoustic version. Same song, so same ISWC. New recording, so your distributor assigns ISRC #2. You add ISRC #2 to the existing work at The MLC and register it at SoundExchange.
- Another artist covers "Paper Moon." Their distributor assigns ISRC #3 to their recording. The composition is still yours and your co-writer's, with the same ISWC. When their recording is linked to your work, you earn composition royalties from their streams.
One ISWC, three ISRCs, and every registration pointing at the right one. That is what clean data looks like.
Common questions artists get stuck on
"My PRO portal does not show an ISWC yet"
ISWCs can take time to be assigned after registration. Register your song anyway and add the ISWC to your other records when it appears. Do not wait on it before registering at The MLC.
"My distributor gave me a new ISRC when I rereleased my single"
If the recording is identical, it should keep the original ISRC. Contact your distributor and ask whether the original code can be used, and update your registrations so they all agree.
"Can I make up an ISWC?"
No. ISWCs are issued through the official system. Never invent any industry code.
FAQ
What is an ISWC code?
An ISWC (International Standard Musical Work Code) is a unique identifier for a musical composition, meaning the song itself. Songwriters usually get one when their song is registered with a PRO or collecting society.
How do I get an ISWC for my song?
In most cases you register the song with your PRO, and an ISWC is assigned to the work through the international system. Check your PRO's member portal for the code after registering.
Is ISWC the same as ISRC?
No. The ISWC identifies the composition, and the ISRC identifies a specific recording. One composition has one ISWC but can have many recordings, each with its own ISRC.
Does a cover song get a new ISWC?
No. A cover uses the same composition, so it keeps the original song's ISWC. The cover recording gets its own new ISRC.