Short answer
The answer, before the reasoning
UK SRS S2 Appendix C3 permits an entity, in its first annual reporting period applying the Standard, to use a GHG measurement method other than the GHG Protocol Corporate Standard only if it used that method in the immediately preceding annual period. The relief is a one-period transition rule, not an indefinite alternative.
Its use is disclosed alongside the compliance statement, and C5 permits the same relief when presenting comparative information in later periods. After the first UK SRS S2 period, the entity should use the GHG Protocol unless an enduring jurisdictional or exchange requirement under paragraphs 29(a)(ii) and B23-B25 applies.
C3 creates a controlled transition from the immediately preceding method to the normal UK SRS S2 basis.
At a glance
1. The exact eligibility test
C3 has two core conditions. First, it applies only in the first annual reporting period in which the entity applies UK SRS S2. Second, the entity must have used the other measurement method in the annual reporting period immediately preceding first application. A method selected only after the decision to adopt UK SRS S2 does not satisfy that transition logic.
2. What C3 changes—and what it does not
C3 changes the method used to measure GHG emissions during the transition period. It does not remove the need to disclose gross Scope 1, Scope 2 and Scope 3 information when otherwise required, explain the method, inputs, assumptions and changes, disaggregate Scope 1 and Scope 2, provide location-based Scope 2 and identify Scope 3 categories.
The method difference should therefore be mapped into the UK SRS S2 disclosure architecture. For example, a jurisdictional inventory might use a different organisational boundary, gas set, GWP table or Scope 2 treatment. The entity needs a difference assessment and, where possible, a bridge to the future GHG Protocol basis.
3. Disclosure alongside the compliance statement
C5 and UK SRS S1 paragraph 73A require use of the relief to be disclosed alongside the statement of compliance. A concise disclosure should name C3, describe the prior method and affected emissions, and explain the planned transition. UK SRS S2 paragraph 29(a)(iii) separately requires the measurement approach, inputs, assumptions, reasons and changes.
4. C3 versus the enduring jurisdictional-method provision
Paragraphs 29(a)(ii) and B23-B25 allow a different method where a jurisdictional authority or exchange requires it for the entity or part of the entity. This can continue while the requirement applies. C3 does not require a legal mandate; it requires prior-period use and is limited to first application. A company can have both situations, but the affected entities and emissions should be separately mapped.
5. C3 versus the C4 Scope 3 relief
The two reliefs have different clocks, evidence and public consequences.
C3 changes the measurement method; C4 can omit Scope 3 disclosure. C3 is limited to the first annual period; C4 has no stated voluntary expiry. C3 eligibility depends on the immediately preceding method; C4 is a UK voluntary disclosure relief. Both must be disclosed alongside the compliance statement, and both can be constrained by a future mandatory UK route.
6. Transition plan and controls
Freeze the prior-period method and calculation package as the C3 baseline.
Map boundaries, gases, scopes, GWP values, factors and Scope 2 treatment against the GHG Protocol.
Identify data fields and system changes needed for the next period.
Run a parallel or bridge calculation for high-risk differences where practicable.
Approve factor libraries, data dictionaries and methodological judgements.
Plan comparative treatment and explain changes in the next report.
Update controls, training, assurance evidence and governance approvals.
7. Hypothetical multinational example
8. Control matrix
9. Common mistakes
Using C3 in a second or later UK SRS S2 period.
Choosing a new alternative method after adoption rather than carrying forward the immediately preceding method.
Assuming C3 removes other GHG disclosure requirements.
Failing to distinguish C3 from B23-B25 jurisdictional relief.
Failing to disclose C3 beside the compliance statement.
Delaying transition work until the end of the first year.
Mixing C3 and C4 in one generic “GHG relief” statement.
10. First-year relief checklist
First annual UK SRS S2 period confirmed.
Prior-period use of the other method evidenced.
Affected scopes, entities and calculations mapped.
Measurement approach, inputs, assumptions and differences disclosed.
Compliance statement identifies C3 use.
Comparative treatment documented.
GHG Protocol transition plan approved.
Enduring jurisdictional requirements separately recorded.
Future mandatory UK route checked.
Sources, status and limitation
This guide reflects UK SRS S2 Appendix C as issued in February 2026. The treatment of a particular jurisdictional method depends on the underlying legal or exchange requirement and the facts of the reporting entity. Final regulatory routes can change relief availability.
Editorial and technical production layer
Quick orientation
Quick orientation
- Applies to
- First-time UK SRS S2 reporters that used a non-GHG-Protocol method in the immediately preceding annual period.
- Primary decision
- Whether C3 is available and how to transition methods without losing traceability or comparability.
- Key sources
- UK SRS S2 paragraph 29(a)(ii), B23-B25 and Appendix C3-C6; UK SRS S1 paragraph 73A.
- Common confusion
- Treating C3 as an enduring jurisdictional exception or as equivalent to the open-ended voluntary Scope 3 relief in C4.
In practice
Eligibility question
| Eligibility question | Evidence | Consequence |
|---|---|---|
| Is this the first annual UK SRS S2 period? | Adoption decision, reporting calendar and source-edition record. | If no, C3 is unavailable for the current-period measurement method. |
| Was the other method used in the immediately preceding annual period? | Prior published report, calculation model, filing or approved methodology. | If no, C3 is unavailable. |
| What emissions and entities did the prior method cover? | Boundary and source mapping. | C3 does not cure missing Scope 1/2/3 disclosure architecture. |
| Is a separate jurisdictional method required? | Law, regulator or exchange rule. | Assess paragraphs B23-B25 as a separate enduring provision. |
Hypothetical scenario
ILLUSTRATIVE WORDING — ADAPT TO FACTS
“This is the Group’s first annual period applying UK SRS S2. The Group has applied Appendix C3 and measured GHG emissions using the [named jurisdictional method] used in the immediately preceding annual period. The principal differences from the GHG Protocol Corporate Standard relate to [boundary / GWP / Scope 2 treatment]. The Group is completing a controlled transition for the next reporting period. Use of C3 is disclosed alongside the statement of compliance.”
Illustrative only. It shows how the decision is made, not wording that can be copied or relied on.
In practice
Feature
| Feature | C3 first-period relief | B23-B25 jurisdictional method |
|---|---|---|
| Trigger | Prior method used in immediately preceding annual period. | Current legal or exchange requirement. |
| Duration | First annual period applying UK SRS S2. | For the duration and affected scope of the requirement. |
| Affected population | As supported by prior method and transition mapping. | Whole entity or affected part. |
| Next control | Transition to GHG Protocol. | Monitor the jurisdictional rule and reconcile group reporting. |
Hypothetical scenario
HYPOTHETICAL EXAMPLE
A multinational used a mandatory national carbon-reporting method in the year before voluntary UK SRS S2 adoption. In the first UK SRS S2 period, it applies C3 for the group measurement while separately identifying a subsidiary that will continue the national method under B23-B25. The group maps boundary and GWP differences, calculates location-based Scope 2, documents Scope 3 categories and prepares a GHG Protocol transition model for the next year. Illustrative scenario only.
Illustrative only. It shows how the decision is made, not wording that can be copied or relied on.
In practice
Control
| Control | Purpose | Evidence |
|---|---|---|
| Prior-use control | Prove eligibility. | Prior report, filed return, methodology approval and calculation archive. |
| Difference assessment | Identify boundary, GWP, factor and classification differences. | Approved mapping and issue log. |
| Version control | Prevent accidental mixing of methods. | Locked models, factor register and change approvals. |
| Parallel calculation | Test next-period readiness and variance. | Bridge outputs and reviewer sign-off. |
| Disclosure control | Keep relief wording consistent with method note and compliance statement. | Final report reconciliation and approval. |
Technical status
PUBLISHING STATUS
This section is for LRA editorial, technical-review, CMS and AI/RAG workflows. The public article ends before this page.
Questions
Questions people ask
Who is eligible for C3?
UK SRS S2 Appendix C3 permits an entity, in its first annual reporting period applying the Standard, to use a GHG measurement method other than the GHG Protocol Corporate Standard only if it used that method in the immediately preceding annual period. The relief is a one-period transition rule, not an indefinite alternative.
How long does C3 last?
UK SRS S2 Appendix C3 permits an entity, in its first annual reporting period applying the Standard, to use a GHG measurement method other than the GHG Protocol Corporate Standard only if it used that method in the immediately preceding annual period. The relief is a one-period transition rule, not an indefinite alternative.
How is C3 different from C4?
C3 changes the measurement method; C4 can omit Scope 3 disclosure. C3 is limited to the first annual period; C4 has no stated voluntary expiry.
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