ISWC vs ISRC: What's the Difference, and Do You Need Both?

Music has two ID systems for two different things, and they get mixed up constantly. If you've ever uploaded a release to a distributor, registered a song with the MLC, or filled in a sync metadata sheet, you've probably been asked for an ISRC, an ISWC, or both. They're not interchangeable, and using one in place of the other is a common reason royalties don't match.

Short answer: an ISRC identifies a specific recording. An ISWC identifies the underlying song. One song can have many ISRCs (one for each recorded version), but only one ISWC. You almost certainly need both. Your distributor issues ISRCs. Your PRO issues ISWCs.

The long version below.

ISRC — International Standard Recording Code

The ISRC identifies a single recording — a specific master. If you record a song in your bedroom, that's one ISRC. If you re-record it for a sophomore album three years later, that's a different ISRC. If you release a remix, an acoustic version, or a sped-up TikTok edit, each one gets its own ISRC.

The format looks like US-ABC-26-12345:

• US — the country of the issuer (the country code, two letters)
• ABC — the registrant code (three characters identifying the issuer, usually a label or distributor)
• 26 — the year of reference, two digits
• 12345 — a unique five-digit serial number per issuer per year

The full spec lives in IFPI's ISRC handbook if you want the standard itself.

Where ISRCs come from:

• Your distributor — DistroKid, TuneCore, CD Baby, UnitedMasters, Stem, Symphonic, AWAL, ONErpm, etc. Every modern distributor issues ISRCs automatically when you upload a release.
• Your label, if you have one. Most labels are registered ISRC issuers.
• Direct from the RIAA in the US, if you want to issue your own. This is overkill for most indie artists — your distributor already does it for free.

ISRCs follow the recording around forever. They're what SoundExchange uses to pay digital performance royalties on the master side, what streaming services use to track plays, and what music recognition tools (Shazam, content ID) match against. Once a recording has an ISRC, do not change it — that breaks every downstream royalty match.

ISWC — International Standard Musical Work Code

The ISWC identifies a composition — the song itself. It's the same code regardless of who performs it, what version it is, or how many times it gets re-recorded. Dolly Parton's "I Will Always Love You" has one ISWC. The Whitney Houston cover, the original 1974 Dolly version, the 1982 re-recording, and every karaoke version share the same ISWC because they're all the same composition.

The format looks like T-123.456.789-0:

• T — fixed prefix indicating an ISWC
• 123.456.789 — a nine-digit unique number
• -0 — a check digit

Where ISWCs come from:

• Your PRO — ASCAP, BMI, or SESAC in the US. When you register a new song with your PRO, they assign an ISWC and report it to CISAC's global ISWC registry. PRS in the UK, SACEM in France, GEMA in Germany — every PRO around the world issues ISWCs.
• Your publisher, if you're signed to one with a relationship to a PRO.

There is exactly one ISWC per song, globally. If two PROs each issue an ISWC for the same song (it happens with co-writers in different societies), CISAC eventually merges them. Your PRO is the source of truth for your songs' ISWCs.

Side by side

Why one song has many ISRCs

Every distinct recording of the same song gets its own ISRC. Real example: a single track that ends up with five ISRCs:

1. The original studio version on the album release
2. The radio edit (shorter, censored vocals)
3. A live version recorded at a festival
4. A remix released six months later
5. The artist's acoustic version on a deluxe edition

All five share one ISWC because they're all the same composition. The publishing royalty pipeline (MLC, PROs, foreign societies) tracks them by ISWC. The recording royalty pipeline (Spotify, SoundExchange, your distributor) tracks them by ISRC.

This matters because if a fan streams the remix and your distributor only registered the original ISRC, that stream might not count toward your master royalties. And if the MLC has the original ISWC but doesn't know that ISRC #4 is a recording of the same composition, the publishing mechanical for that remix could end up unmatched.

When you actually need each one

A practical list:

You need ISRCs to:

• Distribute a release to streaming services and download stores
• Register with SoundExchange to collect digital performance royalties on the master
• Get accurate streaming reports from your distributor
• Match your tracks against content ID systems on YouTube and TikTok

You need ISWCs to:

• Register with the MLC so they can match streaming plays to your composition and pay you mechanicals (see our MLC vs HFA breakdown)
• Register with foreign mechanical and performance societies via sub-publishing
• Get recognized as the writer of the song in CISAC's global registry, which is what PROs around the world reference
• Land sync placements without metadata friction (sync agents and music supervisors expect ISWCs)

You need both. ISRC for the recording side, ISWC for the publishing side. Skipping either one cuts off half the royalty pipeline.

How to get them, in practice

ISRC: if you use a distributor, you already have ISRCs assigned to every track in your catalog. Check your distributor dashboard — they're listed per release. If you self-released and never used a distributor, you can request your own through the RIAA, but for $20 a year a distributor handles it cleanly.

ISWC: sign up with a PRO (ASCAP, BMI, or SESAC in the US). Register each of your songs with them — this is a separate step from registering as a writer. When you register the song, the PRO assigns an ISWC. Important: you actually have to look up and copy that ISWC out of the PRO's portal. Many writers register songs and never bother to record the ISWC anywhere, then later can't fill in the MLC form.

If you have a back catalog without ISWCs, log into ASCAP ACE Repertory (free) or BMI Repertoire Search to look up each song. Same for international PROs. Step-by-step lookup instructions are in our ISWC guide.

What goes wrong

Three patterns we see constantly when we audit a new artist's catalog:

• ISRCs and ISWCs are swapped on a registration. Someone uploads to the MLC and pastes the ISRC where the ISWC should go. The match fails. The royalty sits in the unclaimed pool.
• ISWC is missing entirely. The writer registered with their PRO but never pulled the ISWC into their own metadata sheet. Now their MLC registrations are incomplete.
• Multiple ISRCs for the same song aren't linked back to the ISWC. A re-record or remix has its own ISRC and the MLC has no way to know it should be matched to the same composition. We tie these together when we register a song.

Bottom line

Two codes, two pipelines, both required.

• ISRC = the recording. From your distributor. Used for master royalties.
• ISWC = the composition. From your PRO. Used for publishing royalties.

If you're missing one, half your royalty pipeline is broken. If you're mixing them up on registrations, the broken half goes silently unmatched until someone audits it. We do that audit for our roster — pricing on the pricing page, full model under publishing administration. We take a percentage of what we actually recover — 15 percent on performance royalties, 20 percent on mechanicals — no setup fee, no exclusivity.