How ISRC Registration Gaps Cost Labels Money
A recording can be streaming on Spotify while having no mechanical work registered at the MLC. That gap—measurable, systemic, and worth hundreds of millions annually—is where royalties disappear.
1,581 ISRCs cross-referenced against 11 data sources. Coverage drops from 94.7% to 11.2%. The registration gap is not closing.
TrackForge recently ran a full enrichment pipeline across a mid-size independent label catalog—1,581 unique ISRCs, mostly punk, post-punk, and electronic releases spanning 1978 to 2024. We cross-referenced every recording against eleven data sources: streaming platforms, rights registries, community databases, and unclaimed royalty pools.
The results were not subtle. Of 1,581 recordings, 680 appeared in the MCPS unclaimed pool—potential UK mechanical royalty gaps on 43% of the catalog. From the same label group, we traced a pattern of broken ISRC-to-work linkage across 17 products that accounted for £48,456 in recoverable mechanical royalties. The money had been collected by the CMO. It simply could not be routed to the correct rightsholder because the registration chain was incomplete.
And 84 recordings—5.3% of the catalog—returned zero matches across all eleven layers. No Spotify metadata, no MLC entry, no PRO registration, no community database listing. Valid ISRCs, commercially released music, completely invisible to every rights database we checked. Ghost recordings.
An ISRC registration gap is the difference between a recording's commercial availability and its rights registration across collection societies. It is not a rounding error. It is the structural condition of music rights infrastructure, and until you measure it, you cannot know how much of your catalog is leaking revenue.
The Layer Cake: One Catalog, Eleven Data Sources
Each bar represents the same 1,581 ISRCs checked against a different data source. The drop from 94.7% to 11.2% is the registration gap made visible.
The drop from Spotify (94.7%) to MLC Musical Work (50.0%) is the core registration gap—a 45-point chasm. These recordings are commercially available and generating streams. Spotify has the metadata. The MLC has the sound recording resource. But for half the catalog, no registered mechanical work is linked, meaning royalties from those streams have no verified destination.
The ASCAP column reveals a second fracture. 54.5% of the catalog matched to US performance rights registrations—but only 50.0% had corresponding MLC mechanical work registrations. The same compositions are partially registered for performance royalties but missing from the mechanical system. In the US, performance and mechanical rights are administered by entirely separate organisations, and registration in one does not propagate to the other.
Perhaps the most revealing finding: 33% of the catalog's ISRCs were missing from the label's own registry. They were only discovered by cross-referencing PRS tunecode bridge tables and other external sources. The label did not know these recordings existed in their catalog—and without external cross-referencing, those tracks would have remained unlinked to their rights registrations permanently.
What ISO 3901 Says (and Doesn't Say)
The International Standard Recording Code is governed by ISO 3901, administered by the IFPI. It provides, in the IFPI's own language, "unique and permanent identification of sound recordings across formats and distribution channels." The standard defines who can assign ISRCs—national agencies issue registrant codes to labels, distributors, and producers.
What the standard does not define is who must register them with collection societies. There is no enforcement mechanism requiring a label to link an ISRC to a musical work at the MLC, MCPS, ASCAP, or any other organisation that needs the linkage to route royalties. The IFPI publishes 15 guidance documents covering assignment rules, ownership, and best practices. DDEX "strongly encourages including ISRCs whenever available" in revenue reports. But encouragement is not infrastructure.
An ISRC can exist in Spotify's catalogue, in DDEX delivery messages, and in a label's internal database—and simultaneously be absent from every collection society that pays royalties on the underlying composition. The identifier exists. The cross-registration does not.
An ISRC's journey from assignment to royalty collection. Match rates from the 1,581-ISRC case study.
The Mechanical Black Hole
The catalog-level findings are not anomalous. They reflect a systemic condition visible in the MLC's own aggregate data.
The MLC's Bulk Work-Resource Matching (BWARM) dataset—3.78 billion rows, publicly available—contains 954 million sound recording resources. Of those, 691.7 million (72.5%) have no matched mechanical work. These are recordings with ISRCs, appearing on streaming platforms, generating royalty obligations. But no registered musical work is linked to them in the US mechanical licensing system.
The MLC also holds 57.3 million unclaimed musical work right share records—ownership stakes in compositions where the work is identified, often with an ISWC and writer information, but no rightsholder has claimed the mechanical share. The work is known. The money is waiting. Nobody has filed the paperwork.
Unmatched Resources
Unclaimed Shares
Outreach Recovery
The Music Modernization Act, signed in 2018 and effective January 2021, was designed to solve this. The MMA replaced song-by-song mechanical licensing with a blanket licence administered by the MLC. Five years in, the MLC's own outreach has located "hundreds of previously unregistered rightsholders" and distributed "close to $1 million" in accrued royalties to them. One million dollars against a $569.9 million held balance is 0.18%.
The problem is not that rightsholders are hard to find. The problem is that the infrastructure for linking ISRCs to works to rightsholders does not exist as a unified system.
What It Actually Costs
Return to the 1,581-ISRC catalog. The £48,456 MCPS recovery is instructive not for its size but for its cause. In every case, the ISRCs existed on the recordings. The works were registered with PRS for performance rights. But the mechanical registrations at MCPS were either missing, incomplete, or linked to the wrong entity. The money was collected. It could not be routed.
A 1,581-ISRC catalog yielded 84 ghost recordings (5.3%), a 33% internal registry gap, and a 43% MCPS unclaimed signal rate. The rate will vary by catalog age, genre, and territory—a major-label pop catalog with recent releases will likely fare better than a back-catalog-heavy independent. But the IFPI's International ISRC Database contains over 100 million registrations, and the MLC's own data shows 72.5% of 954 million sound recording resources unmatched to any mechanical work. The pattern observed in one catalog is independently confirmed at aggregate scale. Even a conservative estimate suggests tens of millions of ISRCs are inadequately cross-referenced—present in some systems, absent from others, generating royalties that cannot be routed.
At the MLC alone, $569.9 million in royalties sat in holding accounts across four usage years—approximately $142.5 million per year collected but not distributed. The MLC is a single organisation, in a single territory, covering a single right. MCPS handles UK mechanical royalties. GEMA covers Germany. SACEM covers France. JASRAC covers Japan. APRA AMCOS covers Australia. There are over 230 collection societies worldwide.
The 45-point gap between Spotify coverage and MLC work registration observed in one catalog is not an artefact of catalog size or genre. The MLC's own aggregate data independently confirms it: 72.5% of 954 million resources unmatched across the entire US mechanical system. The structural cause—assignment without cross-registration—applies universally. The global cost of ISRC registration gaps does not run into the hundreds of millions. It runs into the billions.
Closing the Gap
The registration gap is not a technology problem. The identifiers exist. The databases exist. The collection societies exist. What is missing is cross-referencing.
Don't Trust Your Own Registry
33% of the case study's ISRCs were missing from the label's own records. Cross-reference every ISRC against a minimum of three independent sources: PRS tunecode bridge tables, MusicBrainz, and MLC bulk feeds. No single source is complete.
Register Mechanical Rights Separately
54.5% ASCAP vs. 50.0% MLC work match rate. Performance and mechanical rights are different systems with different administrators. Registration at PRS does not register you at MCPS. Treat them as separate obligations.
Audit ISRC-to-ISWC Linkage Annually
Only 23.7% of the catalog had ISWC linkage in the MLC's data. Without that link, mechanical royalties cannot be matched to compositions—regardless of whether both identifiers exist in their respective registries.
Check Unclaimed Pools Before They Expire
43% in MCPS unclaimed. 20.6% in PRS unclaimed. These are published datasets. But after holding periods expire, funds are distributed on a market-share basis. The £48,456 recovery existed because someone checked.
TrackForge's enrichment pipeline automates this cross-referencing across eleven data sources, identifying registration gaps before royalties enter unclaimed pools. The analysis in this article runs automatically for every catalog onboarded to the platform.
The registration gap exists because the music industry's rights infrastructure was built as a collection of independent silos. Closing it requires looking across all of them at once.
Sources and Methodology
| Source | Dataset | Access |
|---|---|---|
| MLC | BWARM bulk data feed (2025-02-23 snapshot) | Public dataset, 3.78B rows |
| MLC | 2024 Annual Report | Published March 2025 |
| IFPI | ISO 3901 / ISRC Standard Documentation | 15 published guidance documents |
| ASCAP | ACE repertory search | Public search interface |
| PRS for Music | Unclaimed works registry | Licensed data |
| MCPS | Unclaimed mechanical royalties | Licensed data |
| MusicBrainz | Community recording database | Open data (CC0) |
| AcoustID | Audio fingerprint database | Open data |
| Discogs | Release and label metadata | API access |
| Spotify | Track and artist metadata | API access |
| DDEX | Communication standards (ISRC formatting) | Published specifications |
| CISAC | CWR v2.1/v2.2 specifications | Published standards |
| US Federal Register | MMA implementation rules (2020-29190) | Public record |
Catalog data anonymised. All match rates are from a single enrichment run across 1,581 unique ISRCs. Individual catalog results will vary based on genre, territory, and release era. This analysis uses TrackForge's enrichment pipeline. The methodology is described in The Black Box Problem.
ISRC Registration Gaps — FAQ
What is an ISRC registration gap?
An ISRC registration gap is the difference between a recording’s commercial availability and its rights registration across collection societies. A track can stream on Spotify (94.7% match rate) while having no mechanical work registered at the MLC (50% match rate). That 45-point gap is where royalties disappear into holding pools.
How much money is lost to ISRC registration gaps?
At the MLC alone, $569.9 million in royalties sat in holding accounts across usage years 2021–2024 — approximately $142.5 million per year collected but not distributed. The MLC is a single organisation covering a single territory and right. With over 230 collection societies worldwide, the global cost runs into the billions annually.
What percentage of MLC sound recordings are unmatched?
72.5% of the 954 million sound recording resources in the MLC’s BWARM database have no matched mechanical work. These are recordings with ISRCs that appear on streaming platforms and generate royalty obligations, but no registered musical work is linked to them in the US mechanical licensing system.
How can labels close ISRC registration gaps?
Labels should: (1) cross-reference ISRCs against at least three independent sources — one case study found 33% of ISRCs missing from the label’s own registry; (2) register mechanical rights separately from performance rights; (3) audit ISRC-to-ISWC linkage annually; and (4) check unclaimed pools at MCPS, PRS, and MLC proactively before holding periods expire.
Related Research
Check any ISRC against Spotify, MusicBrainz, and The MLC in seconds. The same three-source cross-reference described in this article — single or batch, CSV/PDF export, no account required.
Try the tool →$569.9 million sits in MLC holding accounts. £48,456 recovered from a single label's MCPS gap. A forensic look at where unclaimed royalties accumulate — and why they stay unclaimed.
Read the analysis →The 12 lifecycle stages where music royalties disappear — 160+ failure modes mapped across 15 data sources, from creation to distribution.
Read the map →How TrackForge's eleven-layer enrichment pipeline cross-references ISRCs against streaming platforms, rights registries, and unclaimed pools — the methodology behind this article's findings.
Read the methodology →