How to Respond to Supply Chain Carbon Questionnaires
Last updated: April 2026
Summary
- Large customers need your emissions data for their Scope 3 reporting under AASB S2 — this is now a commercial requirement, not optional
- At minimum, provide Scope 1 & 2 totals in tCO2-e, the reporting period, and your methodology
- Being able to respond quickly and accurately is becoming a competitive differentiator in tenders and procurement
Why Are You Receiving Carbon Questionnaires?
If you have received a carbon or sustainability questionnaire from a customer, here is what is happening: your customer is now required (or will soon be required) to report their Scope 3 emissions under AASB S2. Your emissions from producing the goods or services they buy from you are part of their carbon footprint — specifically Category 1: Purchased Goods and Services.
They have two options:
- Use supplier-specific data — actual emissions data provided by you (preferred, more accurate)
- Use spend-based estimates — apply an average emission factor to the dollar value of what they buy from you (less accurate, but a fallback)
Supplier-specific data is always preferred because it is more accurate and shows that the reporting entity's supply chain is engaged. This is why they are coming to you.
What Data to Provide
Minimum Response (Good)
- Total Scope 1 emissions (direct — vehicles, gas, refrigerants) in tonnes CO2-e
- Total Scope 2 emissions (electricity) in tonnes CO2-e — both location-based and market-based if applicable
- Reporting period (e.g., 1 July 2025 – 30 June 2026)
- Methodology — "GHG Protocol Corporate Standard with NGA 2025 emission factors"
- Organisational boundary — operational control or equity share
Better Response (Great)
- Everything above, plus:
- Emission intensity — tCO2-e per $M revenue, or per unit of product/service
- Scope 3 emissions where available (even partial)
- Breakdown by source — how much from fleet, electricity, gas, etc.
- Reduction targets — any commitments to reduce emissions
- Third-party assurance — if your report has been independently verified
Best Response (Excellent)
- Everything above, plus:
- Product-level emissions — the carbon footprint of the specific product or service they purchase from you
- Allocation methodology — how you allocated your total emissions to specific products or customers
- Year-over-year trends — showing emissions trajectory over 2+ years
Common Questionnaire Formats
You may encounter questionnaires in several formats:
- CDP Supply Chain: Standardised online questionnaire covering emissions, risks, targets, and governance. Scored A to D-. Used by major corporates globally
- Custom customer questionnaire: Your customer's own spreadsheet or form. Usually asks for total emissions, methodology, and any certifications
- EcoVadis: Broader sustainability platform covering environmental, labour, ethics, and procurement. Generates a scorecard
- Direct data request: Sometimes just an email asking "what are your carbon emissions?" Respond with a structured summary
What If You Don't Have Your Data Yet?
Don't ignore the request. Here is what to do:
- Acknowledge the request promptly — respond within a week, even if you don't have the data yet
- Provide what you can — if you know your annual electricity consumption (kWh) and vehicle fuel use (litres), share those raw numbers. Your customer can apply emission factors themselves
- Give a timeline — "We are currently measuring our carbon footprint and expect to have Scope 1 and 2 data available by [date]"
- Start measuring now — a basic Scope 1 and 2 calculation takes hours, not months, with the right tool. Collect your electricity bills and fuel records and get it done
The worst response is no response. Ignoring a carbon questionnaire signals to your customer that you are not engaging with sustainability — and gives them a reason to evaluate alternative suppliers who are.
The Commercial Advantage
Responding well to carbon questionnaires is not just compliance — it is a business opportunity:
- Preferred supplier status: Companies are increasingly scoring suppliers on sustainability. A strong carbon response can move you up the procurement list
- Tender differentiation: In competitive bids, being able to provide verified emissions data sets you apart from competitors who cannot
- Relationship strengthening: Proactively sharing your carbon data (before being asked) signals that you are a forward-thinking, reliable partner
- Revenue protection: As AASB S2 Scope 3 becomes mandatory, customers who can't get data from suppliers will look for ones who can provide it. This is a retention issue
Step-by-Step: Responding to Your First Questionnaire
- Read the questionnaire carefully. Understand what is being asked — total company emissions, product-level emissions, or both. Note the reporting period they want
- Measure your Scope 1 and 2 emissions. If you haven't already, collect 12 months of electricity bills and fuel records and calculate your footprint using NGA 2025 factors
- Fill in what you can. Don't leave fields blank — if a question asks for Scope 3 and you don't have it, write "Not yet measured — planned for [date]" rather than leaving it empty
- Include your methodology. State the boundary approach (operational control), emission factor source (NGA 2025), and GWP values used (IPCC AR6)
- Keep a copy. Save your response — you will likely receive similar questionnaires from other customers and can reuse most of the content
- Follow up. Ask your customer if the data was sufficient and whether they need anything else. This builds the relationship
Frequently Asked Questions
Why is my customer asking for my carbon emissions data?
Your customer needs to report their Scope 3 emissions — specifically Category 1 (Purchased Goods and Services). Under AASB S2, Scope 3 becomes mandatory from Year 2. Your emissions from producing the goods or services they buy from you are part of THEIR carbon footprint. They need your data to complete their report. If you can't provide it, they'll either estimate (which is less accurate) or find a supplier who can.
What data should I provide in a carbon questionnaire?
At minimum: your total Scope 1 and Scope 2 emissions in tonnes CO2-e, the reporting period, and the methodology used (e.g., GHG Protocol with NGA 2025 factors). Better responses include: emissions per unit of revenue or per product, Scope 3 where available, a breakdown by emission source, and any reduction targets. The more specific and verifiable your data, the more valuable you are as a supplier.
What if I don't have my emissions data yet?
Start measuring now — a basic Scope 1 and 2 calculation can be done in hours with the right tool. In the short term, be transparent: explain that you're in the process of measuring, provide what data you can (e.g., electricity consumption in kWh), and give a timeline for when full emissions data will be available. This is much better than ignoring the request.
What is the CDP Supply Chain programme?
CDP (formerly Carbon Disclosure Project) runs a programme where large companies request their suppliers to disclose environmental data through standardised questionnaires. If a customer asks you to respond via CDP, you'll complete an online questionnaire covering emissions, climate risks, and reduction targets. CDP scores responses from A to D-minus, and many procurement teams use these scores in supplier evaluations.
Can I refuse to provide carbon data to my customer?
You can, but it's increasingly risky commercially. Large companies are building carbon reporting into procurement criteria. Some are setting requirements that suppliers must disclose emissions data by a certain date to maintain preferred supplier status. Refusing to engage puts you at a competitive disadvantage against suppliers who do provide this data.
Respond to questionnaires in minutes, not weeks
Emisso measures your emissions and generates reports you can share with customers. Built-in questionnaire tools let you respond to supply chain data requests directly.