ISCC EU and ISCC PLUS: mass balance, PoS and audits

ISCC (International Sustainability & Carbon Certification) is a certification system for sustainable and traceable supply chains, run from Cologne. ISCC EU is its scheme for the EU Renewable Energy Directive and is recognised by the European Commission. ISCC PLUS is a voluntary scheme for other markets, such as chemicals, plastics and food, and both work with a mass balance in which every site that handles certified material must be covered by a certificate.

Operium is not ISCC-certified and is not a certification body. ISCC's system documents belong to ISCC; this article summarises them.

What ISCC is and who does the auditing

According to its own timeline, the ISCC Association was set up in 2010 with 13 members, ISCC EU was among the first voluntary schemes recognised by the Commission in 2011, and ISCC PLUS followed in 2014 (iscc-system.org, consulted September 2026).

ISCC does not audit. A company chooses an independent certification body, signs a contract with it and registers with ISCC through the ISCC HUB. The body's auditor carries out the audit and issues the certificate, which then appears in ISCC's public certificate database.

ISCC EU: the scheme recognised under the Renewable Energy Directive

Article 30(4) of the Renewable Energy Directive (RED) lets the Commission recognise voluntary schemes. A recognition decision is valid for no more than five years. Once a scheme is recognised, Member States may not ask for further evidence on the elements it covers.

ISCC EU was recognised by Commission Implementing Decision (EU) 2022/602 of 8 April 2022, amended by Implementing Decision (EU) 2024/3176 of 19 December 2024. The amended text has two end dates:

Covered by the recognition	Valid until
Sustainability criteria for agricultural biomass, greenhouse gas saving data under Article 29(10), the obligation to enter data in the Union or national database, low ILUC-risk certification	13 April 2027
Forest biomass criteria, RFNBO rules under Article 27(6), greenhouse gas data for RFNBOs and recycled carbon fuels	21 December 2029

On the Commission's list (consulted September 2026) an extension of ISCC's scope to co-processing has a positive technical assessment but no decision yet. Before relying on an ISCC EU claim after 13 April 2027, check the Commission's list of voluntary schemes. What RED III requires of these schemes is covered in RED III for biofuels.

ISCC PLUS: outside the Directive

ISCC PLUS is voluntary. It certifies bio, bio-circular (such as used cooking oil), circular and renewable-energy-derived materials for markets including chemicals, plastics and packaging, textiles, food and feed, and energy. Certified finished goods may carry an ISCC logo only after ISCC has approved it and the claim.

	ISCC EU	ISCC PLUS
Purpose	Compliance with RED sustainability and greenhouse gas criteria	Voluntary claims on alternative feedstocks
Legal standing	Recognised by Commission implementing decision	Voluntary, not on the Commission's list
Chain of custody	Physical segregation or mass balance	Physical segregation, controlled blending or mass balance
Mass balance period	Up to 3 months; 12 months for farms and first gathering points sourcing only agricultural or forest biomass	Up to 3 months
Certificate	Per site, 12 months	Per site, 12 months

Once material has been mass balanced at one step, ISCC PLUS requires mass balance at every later step.

How ISCC mass balance works

A mass balance lets certified and non-certified material be mixed physically while the sustainability information stays with the bookkeeping. RED Article 30(1) sets the frame: the sustainability characteristics and sizes of the consignments stay assigned to the mixture, and the consignments withdrawn must be described with the same characteristics, in the same quantities, as those added, balanced over a set period. Implementing Regulation (EU) 2022/996 fills in the detail:

• the balance is closed every three months (twelve for farms and for first gathering points sourcing only agricultural or forest biomass), aligned with the calendar year or another consistent starting point;
• materials count as one mixture only in one container, facility, site or interconnected infrastructure, and only within one product group unless mixed for further processing;
• the characteristics of each set stay together and may not be averaged or split, although the quantity can be withdrawn in parts;
• fuel used for a national obligation is withdrawn from the balance.

ISCC EU 203 adds that book and claim is not allowed under the RED, and that inventory, measured or metered, is the basis of the balance. Where material is processed, site-specific conversion factors adjust the quantities.

Worked example (hypothetical). A trader with storage runs one FAME tank. At the start of the quarter the tank holds 1,200 t, of which 800 t carries sustainability set A. During the quarter 1,500 t arrives with set B and 700 t arrives without a sustainability claim. The trader ships 2,600 t: 800 t under declarations with set A, 1,000 t with set B, and 800 t without a claim. The physical closing stock is 1,200 + 1,500 + 700 − 2,600 = 800 t. The sustainable balance carried forward is 500 t of set B, which does not exceed the 800 t physically in the tank. Declaring 1,000 t under set A would have failed: set A only ever held 800 t.

The proof of sustainability, and who must be certified

Implementing Regulation 2022/996 calls the document a proof of sustainability (PoS). ISCC uses the term Sustainability Declaration and requires one for each incoming and outgoing batch. What it has to contain, and how it relates to the surveyor's quantity and quality papers, is covered in HVO, FAME and UCO inspection.

Under ISCC EU every element that handles sustainable material needs a certificate: first gathering points, collecting points, processing units and traders. Points of origin such as restaurants are usually covered through the collecting point, on the basis of self-declarations. Storage can be certified on its own, as a logistic centre, or as external storage under a certified company. Transport operators are not certified. The recipient must check the supplier's certificate in the ISCC database for the date of physical dispatch. The same chain logic runs through GMP+ in the feed sector, where certified companies do business with other certified companies.

What an ISCC audit involves

An ISCC audit is a system audit. It looks at procedures, records and the mass balance of a site, and differs from an inspection of one cargo; see what an inspection certificate and an inspection report say.

• Initial audit. Focused on whether the procedures are in place. Later audits look back at the claims made in the previous certificate period.
• Non-conformities. Corrective measures within 40 days; no certificate before they are verified.
• Validity. Twelve months, one geographical site.
• Surveillance. For waste and residue chains for biofuels and bioliquids, Regulation 2022/996 requires a surveillance audit within six months of first certification, and an extra one after three months for collecting points and traders that handle both waste and virgin materials such as vegetable oils.
• Oversight. ISCC runs integrity assessments, announced or unannounced. National authorities supervise the certification bodies under RED Article 30(9).

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