When should a company bring in a verifier under the Greenhouse Gas (GHG) Protocol: during the reporting year or after it ends?

Either, says the GHG Protocol Corporate Standard. Verification during the period lets data problems be fixed before the report is drafted, which suits high profile reports. Some programmes ask for independent verification after a report is submitted, often on a random basis. In both cases it cannot close until final data is in.

During the period

The standard says verification during a reporting period allows reporting deficiencies and data issues to be addressed before the final report is prepared. It calls this particularly useful for companies preparing high profile public reports.

After submission

Some GHG programmes require, often on a random selection basis, an independent verification of the inventory after a report is submitted. The standard names the World Economic Forum Global GHG Registry, Australia's Greenhouse Challenge programme and the European Union Emissions Trading System as examples. Those were the programmes in the edition it was written for, so check which still apply.

In both cases, the standard says, the verification cannot be closed out until the final data for the period has been submitted.

An internal verification first

• Verification is often done by an independent external party, but not always. Staff independent of the GHG accounting and reporting process can verify internally.
• Internal and external verification should follow similar procedures and processes.
• For outside readers, external third-party verification is likely to increase credibility significantly, but an independent internal verification can still give valuable assurance on reliability.
• An internal verification is a worthwhile learning step before an external one, and gives the external verifiers useful information to begin with.
• Some companies set up a semi-permanent internal verification team to keep data standards up on an ongoing basis.

A plant calendar

My reading, not the standard's: for a year that runs April to March, an internal review of the first months early in the year catches missing bills while they are easy to find. A verifier can review the method and part-year data during the year, then finish once the final months are in. Ask the verifier whether it will work in two steps and whether that changes its fee or its report.

A two-step plan for an April to March year

• Months 1 to 6: internal reviewer, independent of whoever prepares the figures, checks the first months of bills and the method
• Months 7 to 9: external verifier reviews the method, controls and part-year data. Problems are fixed before drafting
• Months 13 to 14: final months in, report drafted, verifier completes and closes out on final data

An example sequence of mine, not from the standard. The standard only says verification can happen during or after the period and cannot close before final data is submitted.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so each month's figures can be reviewed as the year goes, before the last bill arrives.

• Internal review before external verification
• How long GHG verification takes
• When to start CBAM verification
• A second GHG verification: what changes
• Who at an MSME should face the verifier

Sources: GHG Protocol Corporate Accounting and Reporting Standard (revised edition), chapter 10 (internal assurance, timing of the verification), GHG Protocol Corporate Standard (ghgprotocol.org)

Last reviewed 2026-11-05. The programmes named are from the standard's edition. A scheme you report to may set its own timing, so read its rules first.