Sustainability Certifications Explained: GRS, RCS, ISCC and EN 15343

As sustainability claims come under closer scrutiny from regulators, buyers and advertising watchdogs, third-party certification has become the currency of proof. When a customer wants assurance that your product contains genuine recycled content or sustainable feedstock, a certificate from a recognised scheme is far more persuasive than a self-declaration that anyone could make. But the acronyms - GRS, RCS, ISCC, EN 15343 - are easy to confuse, and holding the wrong one is an expensive mistake.

This guide explains what each of these certifications verifies, who runs them, how the underlying chain-of-custody logic works, and how to decide which is relevant to your business and your customers' markets.

The idea behind chain-of-custody certification

Most of these schemes share a common logic: they verify a claim through the supply chain using chain-of-custody rules. Instead of testing a final product in a lab, they track certified material from its source through every processing and trading step, with audits and documentation at each stage. This is how a recycled-content or sustainability claim on a finished good can be traced back to a verified origin.

Chain-of-custody models range from strict physical segregation, where certified and non-certified material are kept physically apart, to mass balance, where certified input is tracked through a system and credited to output even when materials are physically mixed during processing. Understanding which model a scheme uses matters, because it determines what you must document and how the claim can be worded.

Global Recycled Standard (GRS)

The Global Recycled Standard is managed by Textile Exchange and is one of the most widely requested recycled-content certifications, especially in textiles, apparel and plastics. GRS does more than verify recycled content; it also sets requirements around social and environmental practices and chemical restrictions at certified facilities, making it a fuller compliance package.

• Verifies recycled input and tracks it through the supply chain with a chain-of-custody system.
• Includes social, environmental and chemical criteria at processing sites, not just content verification.
• Typically applied to products meeting a meaningful minimum recycled content, allowing an on-product claim and label.

Recycled Claim Standard (RCS)

The Recycled Claim Standard, also managed by Textile Exchange, is the lighter-touch sibling of GRS. RCS focuses purely on verifying and tracking recycled content through the chain of custody, without the additional social, environmental and chemical requirements that GRS imposes. That makes it simpler and often quicker to achieve.

• Confirms the presence and amount of recycled material and traces it through the supply chain.
• Does not include the social, environmental or chemical criteria that GRS imposes.
• A good fit when a customer wants recycled-content verification but not the fuller compliance package.

ISCC

ISCC, the International Sustainability and Carbon Certification, is a globally recognised scheme covering sustainable feedstocks across sectors including bioenergy, food and feed, and increasingly circular and bio-based materials in chemicals and plastics. ISCC verifies the sustainability of raw materials and traceability along the supply chain, and is widely used where companies need to demonstrate sustainable or renewable feedstock sourcing.

• Covers sustainable, recycled and bio-based feedstocks with strong traceability and sustainability requirements.
• Frequently required in fuels, chemicals and bioeconomy value chains, and by buyers subject to related regulation.
• Uses a mass-balance approach in many applications to track sustainable content through complex, mixed processing.

EN 15343

EN 15343 is a European standard specific to plastics recycling. It provides the framework for traceability of recycled plastic content and for assessing recycled content, giving a recognised technical basis for verifying claims about recycled plastics. Where GRS and RCS are certification schemes, EN 15343 is a standard that underpins how recycled plastic content is traced and calculated, and it is often referenced in the context of plastics-specific claims and regulation, particularly in European markets.

Because it is a technical standard rather than a branded scheme, EN 15343 is frequently used alongside or as the basis for other verification, giving buyers and regulators a common methodology for how recycled plastic content is established and traced through processing.

How to choose the right certification

The right choice depends on your sector, your material, and above all what your customers and target markets require. The safest approach is to confirm the exact standard a buyer demands before you invest, because certifications are not freely interchangeable.

• Textiles, apparel or plastics recycled content: GRS if you want the fuller social and environmental package, RCS if you need recycled-content verification only.
• Sustainable or bio-based feedstocks in fuels, chemicals or the bioeconomy: ISCC.
• Technical traceability and calculation of recycled plastic content, especially for European markets: EN 15343.

How Social Lab helps

Social Lab helps manufacturers and suppliers navigate the certification maze and avoid the costly mistake of pursuing the wrong standard. We start by confirming exactly what your buyers and target markets require, then assess which scheme - GRS, RCS, ISCC or an EN 15343-based approach - fits your material, sector and chain-of-custody model. We help you prepare the documentation and traceability records that certification bodies expect, connect you with accredited certifiers, and structure the evidence so that the resulting certificate strengthens the sustainability claims that increasingly feed into ESG disclosures and value-chain reporting. Certification becomes an investment in credibility rather than a box-ticking cost.

Frequently asked questions