Mass balance accounting
Mass balance accounting is a chain-of-custody method that tracks eligible material entering a system where it may be mixed with other material, then allocates the eligible attribute to outputs under defined rules. The claim is supported by records and reconciliation, not by proving the same molecules remain physically segregated.
In simple terms
The method defines an accounting boundary, balancing period, eligible inputs, conversion factors, losses, outputs, and allocation rules. Records must prevent more attributed output from being claimed than the qualifying input can support after processing. In chemical Recycling, mass balance can connect recycled feedstock introduced into a mixed production system with attributed Recycled content in selected outputs. The permitted claim language and evidence depend on the governing scheme; Mass balance accounting is not automatically interchangeable across certification or regulatory programs.
Why it matters
Some industrial processes cannot economically keep recycled and virgin feedstocks physically separate. A controlled mass-balance route can support investment and Product traceability while preserving quantitative limits. Weak boundaries or double counting can create misleading claims, so users need the applicable rules, audit trail, conversion assumptions, and date before relying on an attributed recycled-content figure.
Example
A chemical plant receives verified recycled feedstock and conventional feedstock into a shared process. It documents quantities, yield losses, and outputs for the approved period, then attributes no more eligible Recycled content than its rules allow. The packaging claim follows the scheme's allocation and evidence requirements; it does not assert that particular recycled molecules are inside that item.
How it differs
Recycled content
Mass balance accounting controls how an eligible attribute is allocated through mixed processing; recycled content describes recovered material attributed to a product and may be established through different chain-of-custody models.
References
Current status
- As of
- Issuer
- HM Revenue & Customs
- Jurisdiction
- United Kingdom
- Instrument or version
- UK Plastic Packaging Tax mass-balance measure
- Status
- The United Kingdom has announced a Plastic Packaging Tax mass-balance approach for chemically recycled plastic from 1 April 2027.
Applicability: The official policy describes a future tax-accounting route. Eligibility, evidence, allocation, certification, and balancing requirements depend on the legislation and guidance applicable from 1 April 2027; the method should not be treated as available for earlier tax periods.