Carbonly's Supplier Portal: How to Collect Scope 3...

To get Scope 3 data from reluctant suppliers, stop asking them to fill in another questionnaire. Carbonly's Supplier Portal lets them upload the invoices, delivery dockets and EPDs they already hold. Each document becomes a Category 1 record traced to its source and to the supplier user who submitted it.

A large industrial supplier in Australia can receive dozens of sustainability questionnaires a year. Different formats. Different granularity. Different scoring rubrics. Different deadlines. The person answering them is often the same person still finalising their own Scope 1 and 2 for last year.

That is the reason your questionnaire got a non-response. It is not indifference. It is workflow collapse on the other side of the email.

Group 1 ASRS reporters are now in their second year, and the scope of assurance widens under the ASSA 5010 phasing, reaching reasonable assurance for financial years beginning on or after 1 July 2030. As Scope 3 comes into assurance, Category 1 (purchased goods and services) is likely to draw the most auditor attention. That category depends almost entirely on supplier data that most Australian suppliers do not currently produce.

Carbonly's Supplier Portal and Supplier Data Chase Agent change what you ask suppliers to do, not how hard you chase them.

Why your questionnaire got no reply

The typical Australian Scope 3 Category 1 workflow looks like this. A sustainability team exports the top 200 suppliers by spend. They email a spreadsheet questionnaire with 30 questions and a two-week deadline. Twenty responses come back. Twelve of them are usable. The rest of the Category 1 total defaults to spend-based EEIO averages, which an assurance provider is likely to query when the methodology mix looks generic.

The suppliers who responded are usually the ones with a dedicated sustainability function. The suppliers who did not respond are usually the ones with the highest emissions per dollar spent. Which is to say, the ones whose primary data would have improved the disclosure the most.

We do not think this is a supplier problem. Nor a buyer problem. It is a coordination problem. Twenty buyers ask the same supplier for the same underlying data in twenty different templates, then complain about response rates.

Suppliers see only what you invite them to

Carbonly's Supplier Portal is a separate authenticated surface, with supplier access scoped per project. A supplier user logs in and sees only what they have been invited to. Not the buyer's other suppliers. Not the buyer's internal emissions ledger. Not commercially sensitive information about the buyer's overall footprint.

The Portal supports multi-user access per supplier, so a procurement person, a sustainability manager, and an operations lead at the supplier organisation can each contribute what they hold. At a mid-size supplier, it is rare for a single person to hold all of the data. The invoice sits with finance. The energy bill sits with facilities. The EPD sits with product engineering. Forcing that data through one sustainability manager is part of why questionnaires stall.

Suppliers cannot see internal user activity, and one supplier cannot see another supplier's uploads.

Supplier documents turned into Category 1 records

The core observation we started from is that supplier-side documents are the same document types Carbonly already reads for the buyer's own Scope 1 and 2 workflow. A supplier invoice. A delivery docket. A product Environmental Product Declaration. A product spec sheet. An energy bill from the supplier's manufacturing facility.

What you get is a supplier's invoice or EPD turned into an emission record, with a source-document link on every record. The document AI engine that reads your own dockets and utility bills runs the same way on supplier uploads. Eight file formats. Five-tier material matching, with low-confidence matches going to a reviewer.

The point is that we did not build a separate, weaker workflow for the supplier side. The supplier gets the same extraction that we run on the buyer's own primary data.

Reminders that reach the right supplier person

Not every supplier will submit on time. That is a permanent feature of the workflow, not a bug to fix.

The Supplier Data Chase Agent tracks which suppliers have submitted, which are overdue, and which are trending toward the deadline. It issues reminder notifications on a cadence you configure, targeted at the individual supplier user rather than a shared inbox. It is not a mass-email blast. Each reminder references what the supplier still owes, links back to their Portal workspace, and is logged on the audit trail as an outbound communication.

Two things about this we want to be honest about. First, an automated reminder cadence lifts response rates but does not close the gap alone. Some suppliers legitimately do not have primary data. The Chase Agent surfaces that fact quickly so you can move on. Second, we are still working on how aggressive the default cadence should be. Too many reminders damages the relationship. Too few and the deadline moves.

Show your auditor who submitted each Category 1 figure

An auditor reviewing your AASB S2 disclosure under ASSA 5010 will ask who submitted a specific piece of Category 1 data, when, and from which document.

Every supplier interaction on the Portal is captured on the audit trail with the actor identified as the supplier user by name and organisation, not conflated with an internal actor. The seven-year retention on audit records applies to supplier submissions the same way it applies to internal ones.

For NGER purposes, if a Scope 1 or Scope 2 datapoint originated from a supplier facility that sits inside your operational control boundary (for example, an operator submitting data for a facility you have equity in), the audit trail records who provided the number and from which source document. This becomes part of the Basis of Preparation the auditor asks for.

Supplier wording matched once, then remembered

When a reviewer corrects a match or assigns a material to an unmatched line on a supplier document, the line text is saved as an alias on that material for your organisation, and later documents with the same wording match through it. That is part of why Category 1 data handling gets easier over time. The first year of a supplier relationship is the expensive one to set up.

The learning stays inside your organisation. Aliases are never shared across tenants.

A primary versus spend-based split your auditor can see

Not every Category 1 record can be primary data. That is a fact, not a failure.

The trust hierarchy we apply is straightforward. Supplier-specific primary data (EPDs, energy bills, product-level LCA) is highest. Industry-average factors combined with supplier-provided quantities sit in the middle. Spend-based EEIO is the fallback. Spend-based records are floored to low data quality, so your AASB S2 disclosure can separate them from primary supplier data.

Because that flag sits on each record, if 40 percent of your Category 1 total is primary supplier data and 60 percent is spend-based, the auditor can see that split at the record level, not only at the summary. We expect limited assurance under ASSA 5010 to ask for exactly that.

We do not have a built-in PCAF data quality scoring engine. What we hold is the source document and the spend-based data quality floor on each record, so a data quality classification can be built as a reporting view on top of it. If your assurance provider wants a PCAF-style score, the inputs are already there. If you want to read more on where spend-based fits legitimately, we covered that in our spend-based emissions accounting guide.

Collect supplier data for every client without the email threads

Most sustainability consultants running Scope 3 engagements for Australian mid-market clients sit in the middle of a large email volume. They are trying to collect primary data from thirty suppliers on behalf of one client, then repeating that pattern across ten clients simultaneously. The coordination overhead is enormous.

The Supplier Portal is designed to be used by consultants as well as by end reporters. A consultant can invite their client's suppliers to a Portal workspace, track submissions, run the extraction, and produce the Category 1 view without sitting inside every email thread. Consultants are buyers of this workflow, not competitors to it. The Portal is the workshop equipment. The consultant is the craftsperson.

For many sustainability consulting practices, supplier engagement is one of the largest hours lines on a Scope 3 engagement. Anything that compresses those hours is upside for the consultant and their client.

Three ways supplier data can reach Carbonly

The Supplier Portal is one of three access modes, not the only one. If a supplier does not want to use the Portal, or if they have a data system that is bigger than a Portal upload flow can accommodate, there are alternatives.

Folder sync. The supplier drops documents into a OneDrive or SharePoint folder shared with you. Carbonly pulls from the folder natively. Common with construction subcontractors who already share dockets by folder.
Per-project email ingestion. The supplier CCs a project-specific email address on their monthly invoices. Extraction runs on the attachment automatically.
The Portal itself. Multi-user access per supplier, scoped per project, with the Supplier Data Chase Agent following up on your configured cadence.

The point is that Carbonly imports supplier data from wherever the supplier already has it. If a supplier has a legitimate reason not to use the Portal, the workflow does not collapse.

What the Portal does not do

The Portal does not chase harder for its own sake. If a supplier genuinely has no primary data available, the reminder cadence stops and the record falls back to industry-average or spend-based, with the methodology label recorded.

The Portal does not manufacture data quality that is not there. A rough spreadsheet with round numbers is still a rough spreadsheet; the record keeps the source document, so the auditor can see what each number rests on.

The Portal does not replace the buyer's judgment about which suppliers matter. You still decide who to invite. The 20/80 rule usually applies. Your top 20 Category 1 suppliers by spend account for most of the material Scope 3, and the Portal is best deployed against that group first, not scattered across 500 tail suppliers who each represent 0.1 percent of your footprint.

Start with your top 20 suppliers

Rank your Category 1 spend. Top 20 suppliers by dollar value. Invite them to the Portal. Track response rate over a quarter. Two things will happen.

The suppliers who respond will produce primary data, and the corrections your reviewers make along the way become learned aliases for year two. The suppliers who do not respond will either eventually respond after two or three reminder cycles, or they will confirm they do not have primary data available, in which case you spend-base that portion of Category 1 with the methodology label recorded and move on.

The point of the Portal is not that every supplier gives you what you want. The point is that the workflow scales. Twenty relationships you manage properly beat two hundred spreadsheets you send once and then hope for.

If you want primary Category 1 data from your actual top 20 suppliers, email hello@carbonly.ai and we'll show you the Portal against that list. Pricing is per-project (Small, Medium, Large, Enterprise) plus a $100 per month workspace minimum. Supplier Portal seats are included at each tier, so you are not paying per supplier user.

Carbonly's Supplier Portal: How to Collect Scope 3 Data From Suppliers Who Don't Want To Give It To You