ISO 22095-2 is the international standard that sets the rules for running a mass balance chain of custody system, so a claim built on mass balance means the same thing from one company to the next.
Published in 2026, it turns the mass balance model from the parent standard ISO 22095 into a detailed rulebook, for the people who build and trust these systems.
A mass balance claim used to be only as trustworthy as the scheme behind it, and no two schemes agreed. ISO 22095-2 gives them one rulebook, which is what turns "we use mass balance" into a claim a buyer or an auditor can actually check.
The basics of ISO 22095-2
Here is the standard in one view before we get into how it works.
| Standard | ISO 22095-2 |
| Full title | Chain of custody, Part 2, requirements and guidelines for mass balance |
| Current edition | 2026 (first edition) |
| Status | Published |
| Type | Requirements and guidelines standard, not a certification |
| Published by | ISO/TC 308 (Chain of custody) |
| Family | Part 2 of the ISO 22095 series (base ISO 22095, plus Part 3 for book and claim) |
What the mass balance model is
Before the rules make sense, three terms need to be clear.
Chain of custody is the trail that keeps a claim attached to a material as it moves through a supply chain. Mass balance is one way to hold that trail when the material cannot be kept physically apart.
Mass balance is an accounting method. You track the claimed material by quantity, not by keeping it separate. Certified feedstock goes into a process and mixes with conventional feedstock.
An equal quantity of the output can then be sold with the claim, even though any single item may not contain the certified material. The books carry the claim, not the molecules.
Two more terms do the heavy lifting:
- System boundary. The edges of the accounting: which sites and materials are counted, and how long each balancing period runs (a quarter, a year). A claim only balances inside its boundary.
- Conversion factor. Processes lose material. The conversion factor is how a claimed input volume translates into output after that yield or loss, so the sums stay honest.
How a mass balance system works
A mass balance system is really a few decisions you set up once and then apply every balancing period. In order:
- Set the system boundary. Decide which sites and materials are in, and how long the balancing period is.
- Record the claimed input by quantity as certified material enters.
- Apply the conversion factor so the input volume becomes the smaller output volume the process actually yields.
- Attribute an equal, adjusted quantity of output as claimed, assigned to specific batches.
- Reconcile the books so you never attribute more claimed output than went in.
A worked example makes it concrete. Say a converter feeds 100 tonnes of plastic into a shared line, and 30 tonnes of it is certified recycled. After a 90% process yield the line makes 90 tonnes of product.
Under mass balance the converter can label 27 tonnes of that output as recycled (30 tonnes at 90%) and assign it to specific batches.
Which physical pellets carry the recycled molecules does not matter. What matters is that the claimed output never exceeds the claimed input once the conversion is accounted for. That cap is what stops the same recycled tonne being sold twice, the failure mode ISO 22095-2 exists to close off.
The two ways to attribute a claim
ISO 22095-2 sets out two methods for turning claimed input into claimed output. A system picks one and states which it uses.
- The rolling average percentage method. You work out the claimed share of everything that went in across the balancing period, then apply that share to the output. If 30% of the input was certified, 30% of the output can carry the claim, spread across the batches.
- The credit method. Claimed input earns credits that sit in a balance. Those credits are allocated to specific output batches, up to the number available. A batch is either fully claimed or not, rather than everything carrying a percentage.
The difference is not cosmetic. The rolling average spreads the claim thinly and evenly; the credit method concentrates it, so some batches are fully claimed and others carry nothing. Which one fits depends on how the material and the buyers work.
Who needs ISO 22095-2
ISO 22095-2 is written first for the people who build mass balance systems, and then for everyone who has to trust one.
- Scheme owners and standards developers designing a mass balance system, often called the requirements setters. The standard reads as a design guide for them more than a daily how-to.
- Producers and converters applying mass balance in plastics, chemicals, biofuels, agri-food and packaging.
- Brand owners making a recycled or renewable content claim on that basis.
- Auditors and certification bodies checking that a system holds together.
ISO 22095-2 and recycled content claims
This is where the standard stops being abstract for a producer.
The EU's Packaging and Packaging Waste Regulation (PPWR) sets minimum post-consumer recycled (PCR) content for plastic packaging. The targets start to apply from 2030, with a second tier in 2040, and from 2030 the PPWR Declaration of Conformity has to attest the recycled percentage a producer claims.
Recycled content in plastics, chemically recycled feedstock especially, is very often accounted through mass balance, because recycled and virgin material get mixed in shared processes. ISO 22095-2 does not set the legal target or force anyone to use mass balance.
What it does is make a mass balance recycled-content claim credible, comparable and ready for the verification an auditor or regulator will ask for.
For a producer, that turns a soft claim into evidence. Keeping the record of which products used certified feedstock, and how much, is exactly the kind of product data an Extended Producer Responsibility (EPR) platform is built to hold.
Mass balance vs the other chain of custody models
The base standard ISO 22095 defines five chain of custody models. Mass balance is one of them, and the quickest way to place it is to see all five side by side.
| Model | What happens to the claimed material |
|---|---|
| Identity preserved | Kept apart and traceable to a single source the whole way |
| Segregated | Kept physically separate, but may come from several approved sources |
| Controlled blending | Mixed in a set proportion that shows up in the physical output |
| Mass balance | Mixed freely, tracked by quantity, an equal amount of output claimed |
| Book and claim | No physical link at all, the certificate is traded on its own |
The two neighbours are the ones people mix up with mass balance. Controlled blending also mixes claimed and non-claimed material, but the set proportion is physically present in every unit of output. Mass balance drops that guarantee and tracks by volume instead.
Book and claim goes further and cuts the last physical link, so the certificate is traded on its own. Mass balance still needs the claimed material to physically enter the same system.
ISO 22095-2 is the rulebook for mass balance. Its sibling ISO 22095-3 does the same job for book and claim, and both arrived in 2026 alongside an amendment to the base standard ISO 22095, which sets the shared terminology and the five models above.
ISO 22095-2 questions answered
Short, plain answers to the questions people ask most about ISO 22095-2.
What is ISO 22095-2?
ISO 22095-2 is the international standard, published in 2026, that sets the requirements and guidelines for a mass balance chain of custody system. It builds on the parent standard ISO 22095 by turning the mass balance model into a detailed rulebook, so a claim made on that basis means the same thing across companies and sectors.
Is ISO 22095-2 a certification?
No. It is a requirements-and-guidelines standard you design a system against and reference, not a scheme you get a certificate for. The certificate, when there is one, comes from the sector scheme or the auditor that uses these rules, not from ISO 22095-2 itself.
What edition of ISO 22095-2 is current?
The first edition, published in 2026. It arrived alongside ISO 22095-3, which covers book and claim, and both extend the base ISO 22095 standard from 2020.
What is the difference between the rolling average and credit methods?
Both turn claimed input into claimed output, but they spread it differently. The rolling average percentage method applies the claimed share evenly across all output, so every batch carries the same percentage. The credit method banks claimed input as credits and assigns them to specific batches, so some output is fully claimed and the rest carries nothing.
Does mass balance mean my product actually contains recycled material?
Not necessarily in any single unit. Mass balance guarantees that the claimed quantity of recycled material really entered the system, not that the specific item you are holding contains it. That is the whole point of the model, and the reason it needs a standard like ISO 22095-2 to stay trustworthy.
How does ISO 22095-2 relate to ISO 22095 and ISO 22095-3?
ISO 22095 is the base standard that defines the shared terminology and the five chain of custody models. ISO 22095-2 is the detailed rulebook for one of them, mass balance. ISO 22095-3 is the matching rulebook for book and claim.
How does ISO 22095-2 connect to EU packaging rules?
The PPWR requires minimum recycled content in plastic packaging from 2030, and the recycled percentage has to be declared. Because that recycled content is often accounted through mass balance, a system built to ISO 22095-2 is what makes the declared figure credible and checkable.
Who has to follow ISO 22095-2?
No law names the standard directly, so it is not mandatory in that sense. In practice, anyone building or operating a mass balance system that has to be trusted, plus the auditors checking it, follows ISO 22095-2 because it is the shared reference for getting mass balance right.
