What an assessor will ask for

From FY2026-27, the top 1000 listed companies need their BRSR Core assessed or assured (SEBI circular 2023/122, with the “assessment or assurance” wording from SEBI circular 2025/42). Whichever route you take, the engagement comes down to one test: can someone who did not prepare the number get back to its source and arrive at the same figure?

This post is about preparing for that test. It describes good practice, not a regulatory checklist: your assessor or assurance provider will set their own procedures.

The question behind every request

Assessors rarely ask “is this number right?” in the abstract. They pick a reported figure, often on a sample basis, and follow it down:

The reported value. What does the disclosure say, and for which boundary and period?
The calculation. Which inputs, which formula, which factors?
The inputs. Which facility entries make up the total, and do they add up?
The source records. Which bill, invoice, meter log or register supports each input?
The approvals. Who entered each value, who reviewed it, and when was it locked?

If any step is missing, the request comes back to you, and each one is answered separately. That back-and-forth is what makes a first engagement slow.

The evidence file for each Core KPI

For every Core KPI, have these six things ready:

The reported value, with its boundary and period. State which facilities are included and on what basis (for example, financial or operational control), and justify any exclusion. The boundary must be written down, not remembered.
The calculation, with real numbers. A formula in a spreadsheet cell is not enough. Show the calculation with the period’s actual inputs. For ratios, including intensity per rupee of turnover adjusted for PPP, show the numerator and the denominator and where each came from.
The factors, with source and version. Every emission factor and net calorific value needs a source precise enough to find and a version that matches the reporting year. Expect questions on grid electricity: which edition of the CEA CO₂ Baseline Database did you use, and why that one? Our post on Scope 2 in India covers this.
Per-facility values that add up to the reported total. The assessor will reconcile the sum of your facilities to the figure you report.
Source documents linked to the values they support. Evidence should sit next to the value, not in a folder someone has to search. For each monthly entry at each facility, the assessor should be able to open the document and see the same figure.
The approval trail and a record of changes. Who entered each value, who reviewed it, whether it was returned and why, and who locked it. The same person should not both prepare and approve. If a value changed after review, show the before and after, who changed it and why. A trail that records changes is only useful if it can be shown not to have been edited itself. If your approvals happened in email, expect to be asked for the emails.

Organise by KPI, not by department

Many companies keep ESG evidence the way it arrives: an HR folder, an EHS folder, a finance folder, one per plant. An assessor works the other way round, starting from a KPI. Re-organising a year of files by KPI in the weeks before the engagement is avoidable rework. Set up the structure at the start of the year, and fill it as values are approved.

Check your provider’s independence

The company must ensure its assessment or assurance provider has no conflict of interest: the provider and its associates may not sell it products or other services, including consulting. SEBI set the rule in 2023 and extended it to assessment in March 2025. Check it before you appoint anyone; BRSR Core explained sets out the rule.

A short self-test

Pick one Core KPI from last year, for example your total energy consumption. Time how long it takes to answer these, without asking anyone:

Which facilities are in the total, and why are any excluded?
What is the value for one facility in one month, and which document supports it?
Which conversion factor or NCV was applied, from which source and edition?
Who approved that monthly value, and when?
Has the value changed since it was approved?

If any answer needs an email thread or a phone call, that is where to start.

Where Sustano fits

Sustano was built around this test. Every approved figure carries its evidence, calculation and approvals, and can be followed back to its emission factor and source entries. One person enters a figure and another approves it, and your assessor has their own access but cannot change data. They can verify the audit trail independently, without relying on Sustano. For each BRSR Core attribute, the evidence pack brings together the file described above. See how Sustano supports assessors.

This post refers to SEBI requirements for information only; it is not legal advice. Refer to the linked circulars. Last reviewed 29 September 2026.

All posts · Resources