# 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. *Published by [TrackForge](https://trackforge.studio) — 2026-03-10* --- ## The Gap Nobody Measures 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 The full enrichment results form a layer cake of declining coverage. Each row represents the same 1,581 ISRCs checked against a different data source: | Data Source | ISRCs Matched | Match Rate | |---|---|---| | Spotify | 1,497 | 94.7% | | MLC Sound Recording | 1,419 | 89.8% | | MLC Release | 1,416 | 89.6% | | ASCAP (US Performance) | 861 | 54.5% | | MLC Musical Work | 791 | 50.0% | | MCPS Unclaimed Pool | 680 | 43.0% | | MusicBrainz | 569 | 36.0% | | AcoustID Fingerprint | 543 | 34.3% | | Discogs | 497 | 31.4% | | MLC ISWC Linkage | 374 | 23.7% | | PRS Unclaimed Pool | 326 | 20.6% | | MLC Unclaimed Shares | 177 | 11.2% | 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. The result is a gap by design. 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. --- ## 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. The financial consequence is published in the MLC's annual reports: | Usage Year | Total Held | Unmatched | Unclaimed | |---|---|---|---| | 2021 | $90.9M | $44.4M | $44.9M | | 2022 | $106.5M | $53.7M | $49.1M | | 2023 | $174.5M | $92.0M | $73.1M | | 2024 | $197.0M | $110.3M | $76.7M | | **Total** | **$569.9M** | **$300.3M** | **$243.9M** | The held balance has more than doubled in three years — from $90.9 million to $197.0 million. The MLC has made progress through reprocessing: for 2021 usage, reprocessing matched an additional $63.6 million that was initially unmatched. For 2023, the figure was $54.9 million. But new unmatched royalties accrue faster than reprocessing can clear the backlog. 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. This is not a one-catalog problem. Consider the arithmetic: 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. Now multiply. MCPS handles UK mechanical royalties. GEMA covers Germany. SACEM covers France. JASRAC covers Japan. APRA AMCOS covers Australia. Each maintains its own registry, its own matching logic, and its own unmatched pool. 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: What Labels Should Do The registration gap is not a technology problem. The identifiers exist. The databases exist. The collection societies exist. What is missing is cross-referencing — systematic verification that a recording registered in one system is also registered in every other system that needs to know about it. **1. Don't trust your own registry.** The case study found 33% of a catalog's ISRCs missing from the label's internal records — discovered only through PRS tunecode bridge tables, MusicBrainz community data, and MLC bulk feeds. Cross-reference every ISRC against a minimum of three independent sources. No single source is complete. Coverage requires triangulation. **2. Register mechanical rights separately from performance rights.** The 54.5% ASCAP vs. 50.0% MLC work match rate proves the point: performance and mechanical rights are different systems with different administrators. Registration at PRS does not register you at MCPS. Registration at ASCAP does not register you at the MLC. Treat them as separate obligations, because they are. **3. Audit ISRC-to-ISWC linkage annually.** Only 23.7% of the case study catalog had ISWC linkage in the MLC's data. Without that link, mechanical royalties for streamed recordings cannot be matched to the underlying composition — regardless of whether both identifiers exist in their respective registries. The identifiers are not the problem. The linkage between them is. **4. Check unclaimed pools before they expire.** 43% of the catalog appeared in the MCPS unclaimed pool. 20.6% appeared in PRS unclaimed. These are published datasets — not secrets. But unclaimed pools have holding periods, and after expiration, funds are distributed to other members on a market-share basis. The £48,456 MCPS recovery existed because someone checked. The money that nobody checks for goes to someone else. 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, which cross-references recordings against commercial metadata, rights registrations, and unclaimed royalty pools. The methodology is described in [The Black Box Problem](/black-box).* --- *Source: [How ISRC Registration Gaps Cost Labels Money](https://trackforge.studio/research/isrc-registration-gaps)*