Why Your Enterprise Clients Are Suddenly Asking for Your Carbon Data

Something Changed in 2024 — Here's What

If you have never been asked about carbon before and suddenly received two or three sustainability questionnaires this year, you are experiencing the downstream effect of CSRD enforcement.

The Corporate Sustainability Reporting Directive requires all EU companies with 500+ employees to publish a sustainability report including full Scope 3 supply chain emissions — starting with financial years from 2024. The first filings hit public registers in 2025. The second wave — companies with 250+ employees and €40m+ turnover — started in 2025 with filings due in 2026. Smaller listed companies follow in 2026.

That timeline directly explains why the questionnaires started arriving: your clients have a legal deadline, and they need your data to meet it.

Why Your Emissions Appear in Their Report

Under the GHG Protocol Corporate Standard — the methodology underpinning CSRD — a large company's Scope 3 Category 1 covers the emissions embedded in everything it purchases from suppliers. For a manufacturer, that includes the metal, plastic, chemicals, and components you supply. For a retailer, it includes your products. For a service company, it includes your professional services.

Your Scope 1 and 2 emissions represent the baseline data your client uses to estimate their Category 1 footprint. Your Scope 3 adds further upstream context. The more accurate the data you provide, the more accurate their CSRD filing.

Which Clients Are Most Likely to Ask You

The questionnaires are travelling downstream through supply chains in waves. The first-movers are:

If you supply any company with 500+ employees in any of these sectors, you will almost certainly receive a questionnaire in the next 12–18 months if you have not already.

What Happens If You Don't Respond

Enterprise procurement systems score suppliers on sustainability response rates. The consequences of non-response are practical:

• Supplier risk flag — your profile is marked as high ESG risk in the buyer's system
• Tender exclusion — in some sectors (notably German automotive and UK public sector), sustainability questionnaire completion is now a minimum qualification criterion, not a scoring metric
• Contract review — CSRD-compliant buyers must demonstrate to auditors that their Scope 3 calculation is based on supplier data. A non-responding supplier creates a gap they must document
• Relationship friction — procurement managers will escalate to account managers, creating unnecessary relationship pressure

What Responding Looks Like in Practice

The data request is simpler than it appears. Your client needs:

1. Your Scope 1, 2, and 3 emissions in tCO2e for the most recent full year
2. Your calculation methodology (GHG Protocol + DEFRA 2023)
3. A verification trail — a Carbon Passport URL or other documented evidence

DeCarbonOPS lets you generate all three in under 20 minutes. Your Carbon Passport is publicly accessible at a permanent URL — the buyer's procurement system records it, and you never need to fill in the same form twice for the same client.

Will This Requirement Go Away?

No. CSRD is now law across all 27 EU member states and the UK Government has signalled equivalent reporting requirements under TCFD. The supply chain data collection process is in its early stages — pressure will increase, not decrease, over the next three to five years. Companies that set up their carbon reporting infrastructure now will find it progressively easier to respond to new requests.