# How does an auditor verify activity data in a GHG inventory?

Canonical: https://senseible.earth/answers/how-auditors-verify-activity-data

An auditor checks activity data in three ways. They trace a sample of reported quantities back to invoices, bills and meter readings. They trace a sample of source documents forward into the totals to test completeness. And they reconcile your totals against independent records such as purchase ledgers, stock registers and production.

## Step 1: understand how the numbers were built

Before testing anything, the verifier maps the data flow: which documents feed each emission source, who enters them, which spreadsheet or system adds them up, and where factors are applied. ISO 14064-3 calls this assessing the risk of misstatement. Sources that are large, manual or estimated get the most testing.

## Step 2: vouching and tracing a sample

- Vouching (testing accuracy): pick reported lines, for example March diesel of 4,200 litres, and find the fuel invoice or slip that supports the quantity, unit, date and site.
- Tracing (testing completeness): pick source documents from the purchase ledger or the discom account, and check each one appears in the inventory in the right month.
- Sample size grows with the size of the source and the level of assurance. Large sources may be tested in full.

## Step 3: reconcile to records the carbon team does not control

- Fuel bought per invoices against accounts payable or the general ledger.
- Fuel used against purchases adjusted for opening and closing stock in the store register.
- Electricity units against the discom bills for every connection, including small ones.
- Energy use against production: a month where output rose but kWh fell gets a question.

## Step 4: check periods, units and recalculation

Verifiers look for bills that straddle two reporting periods, kVAh read as kWh, kilolitres read as litres, and net-metered units counted as consumption. Then they recalculate a sample: quantity times the stated factor, to the stated rounding. Any difference above their materiality threshold is reported to you as a misstatement to correct.

## Worked example: reconciling a year of diesel

- Diesel bought per invoices: 52,000 litres
- Opening stock 3,000 litres, closing stock 5,000 litres
- Diesel used: 52,000 plus 3,000 minus 5,000 = 50,000 litres
- Scope 1: 50,000 x 2.68 kg CO2 per litre (IPCC 2006 default) = 134,000 kg CO2, 134 t
- If the inventory reports 52,000 litres instead, it overstates by 2,000 x 2.68 = 5,360 kg CO2

The stock register is the independent record here; without it, purchases are only a proxy for use.

## What Senseible does here

Senseible links every line to its source invoice or bill, records a SHA-256 fingerprint of each file and keeps a hash-chained ledger, so a verifier can vouch and recalculate without hunting for paper. Its Verified status means its own rule checks passed; the sampling, reconciliation and opinion remain the auditor's work.

- [What auditors check in GHG assurance](https://senseible.earth/answers/what-auditors-check-in-ghg-assurance)
- [Documents needed for carbon verification](https://senseible.earth/climate-intelligence/documents-needed-carbon-verification)
- [What audit-grade carbon data means](https://senseible.earth/climate-intelligence/audit-grade-carbon-data-what-it-actually-means)

Sources: [ISO 14064-3:2019, Specification with guidance for the verification and validation of GHG statements](https://www.iso.org), [SEBI circular on BRSR Core, 12 July 2023](https://www.sebi.gov.in/sebi_data/attachdocs/jul-2023/1689087475880.pdf), [2006 IPCC Guidelines, Volume 2 Energy (diesel default)](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html)

Last reviewed 2026-10-15.