ISCC PLUS updates mass-balance guidance — implications for TPO and rCB supply chains
Vienna, 24 September 2026 — ISCC has released Version 1.1 of its ISCC PLUS Mass Balance Guidance Document, providing further clarification on bookkeeping, attribution options and the calculation of certified shares under ISCC PLUS.
The update is particularly relevant for companies operating ISCC PLUS-certified tire pyrolysis oil (TPO), recovered carbon black (rCB) and related circular-material supply chains, especially where ISCC PLUS and ISCC EU certification coexist within the same site or value chain.
One important clarification concerns cross-scheme bookkeeping. Where a site is certified under both ISCC EU and ISCC PLUS, the respective mass-balance systems must remain separated, and the same quantity cannot be accounted for under both schemes. Material may move from ISCC EU into ISCC PLUS bookkeeping, but the applicable rules depend on the certification system under which the material is accounted for at each stage.
The guidance also provides additional details on Free Attribution, Proportional Attribution and the calculation of certified shares. Attribution remains subject to safeguards including chemical connectivity, actual physical output, site-specific bookkeeping and appropriate operational data.
For ELT pyrolysis operators, these requirements may be relevant when assigning certified characteristics across different outputs such as TPO, recovered carbon material and other process streams.
Importantly, the updated document is an ISCC PLUS guidance document. It does not automatically change the separate requirements applicable under ISCC EU. This distinction is particularly important for TPO supply chains serving regulated fuel markets or seeking claims under the EU Renewable Energy Directive framework.
Weibold therefore recommends that ISCC PLUS-certified ELT pyrolysis operators and downstream TPO/rCB users review their mass-balance procedures before the revised ISCC PLUS 203-2 Chain of Custody framework becomes mandatory from 1 January 2027.
Weibold will continue to monitor the implementation of the revised ISCC PLUS mass-balance framework and its implications for ELT pyrolysis, TPO, rCB and downstream refinery and chemical applications.
About Weibold
Robert Weibold GmbH is a globally active, independent consulting firm specializing exclusively in tire recycling and tire pyrolysis. Since 1999, Weibold has advised recyclers, investors, technology providers, tire manufacturers, and other industry stakeholders on market, technology, and strategic development. Headquartered in Vienna with a presence across four continents, Weibold combines international industry expertise with proprietary market intelligence and a database covering more than 1,000 stakeholders across the global tire recycling value chain.
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Weibold is an international consulting company specializing exclusively in end-of-life tire recycling and pyrolysis. Since 1999, we have helped companies grow and build profitable businesses.
