UK SRS S1 Comparatives, Estimates and Errors: First-Year Reporting Guide

Technical status. Final UK SRS S1 was published for voluntary use on 25 February 2026. Appendix E reliefs may be changed or overridden when UK law or regulation requires application. As at 2 August 2026, proposed FCA rules were not final.

Limitation. Educational material. It does not determine whether a change is an estimate or error, whether retrospective revision is impracticable, or how future UK regulatory transition rules apply to a particular entity.

Comparatives and corrections affect more than a sustainability table. They influence trend explanations, target performance, management credibility, connected information, assurance scope and the statement of compliance.

The most common errors arise when teams use one word — “restatement” — for several different events:

first-year transition relief;

climate-only relief;

a revised estimate based on new evidence about prior-period conditions;

a current-period change in estimate;

a redefined or replacement metric;

a newly introduced metric;

correction of a material prior-period error; or

an amount that cannot be revised because doing so is impracticable.

Each has a different technical basis and disclosure consequence. Classification should happen before the report is drafted.

Appendix E1 says that an entity is not required to disclose comparative information in the first annual reporting period in which it applies UK SRS S1.

The relief reduces the current publication burden. It does not mean that the entity should ignore historical information. Prior data may still be useful for:

setting baselines and targets;

explaining trends and current performance;

identifying risks and opportunities;

testing the reasonableness of estimates;

connecting sustainability information to financial planning;

preparing future comparatives; and

providing voluntary historical information where it is reliable and clearly labelled.

A first-year reporter should decide whether to present voluntary historical information and control it carefully. Do not present incomplete prior-year data as if it were fully comparable. Explain differences in boundary, method, data quality, assurance status and reporting purpose.

Practical first-year rule. Build the current-year data dictionary and evidence file as though every amount will become next year's comparative. Relief from publication is not relief from establishing a controlled baseline.

Unless another UK Sustainability Reporting Standard permits or requires otherwise, paragraph 70 requires comparative information for the preceding period for all amounts disclosed. It also requires comparative narrative and descriptive information when useful for understanding current-period disclosures.

Comparatives therefore extend beyond headline KPIs. Amounts can include:

metrics and target performance;

current and anticipated financial effects;

expenditure and resources;

exposures and populations;

scenario or sensitivity amounts;

balances and movements; and

other quantified narrative information.

Narrative comparatives may be useful when governance, strategy, risk-management processes, boundaries, assumptions or actions changed. The entity should not repeat the entire prior-year narrative. It should explain the changes needed to understand the current period.

Control point. The disclosure matrix should flag every current-year amount and ask whether a preceding-period amount is present, relieved, impracticable or not applicable.

Appendix E2 ordinarily requires UK SRS S1 and UK SRS S2 to be applied at the same time. Appendix E3 permits an entity to disclose exclusively climate-related risks and opportunities and to apply UK SRS S1 only insofar as it relates to climate disclosure.

Compliance statement

Paragraph 73A says that an entity using E3:

is not permitted to assert compliance with UK SRS S1; and

must disclose that it has used E3.

The entity might still be able to assert UK SRS S2 compliance if it meets the relevant conditions, but it must disclose use of the relief alongside that statement.

Climate comparatives

E4(a) says an entity using E3 does not need climate-related comparative information in the first annual period in which it applies the Standard.

Wider-sustainability comparatives

E4(b) says non-climate sustainability comparatives are not required until the second annual reporting period in which the entity ceases to apply E3.

An illustrative voluntary pathway is:

Year 1: E3 climate-only reporting — no climate comparatives required;

Year 2: the entity ceases E3 and begins wider sustainability reporting — no wider-sustainability comparatives required; and

Year 3: the second annual period after ceasing E3 — Year 2 wider-sustainability information becomes the preceding-period comparative.

Appendix E5 makes application and availability of E3 subject to future UK law and regulation when the Standard is required.

Figure 1. Full application and climate-only relief create different comparative timetables and claim consequences. Original London Reporting Academy practitioner visual.

Paragraph B50 addresses a specific event. If the entity identifies new information about an estimated amount disclosed in the preceding period and that information provides evidence of circumstances that existed in that period, it must:

1. disclose a revised comparative amount reflecting the new information;

2. disclose the difference from the amount previously reported; and

3. explain why the comparative was revised.

This is not automatically an error. The prior estimate may have been reasonable using the information then available.

Illustrative example — supplier emissions estimate

In 2027, a company receives improved 2026 supplier activity data. If the new data provides evidence about supplier activity and conditions that existed in 2026, B50 may require a revised 2026 comparative estimate, subject to B51.

If the change instead reflects a new supplier contract, a changed production process or another 2027 condition, it is a current-period development. The 2027 or forward-looking estimate changes; the 2026 comparative is not rewritten for a condition that did not exist then.

Forward-looking metrics

B51 says the entity need not revise a comparative for a forward-looking metric. It may revise it if doing so does not use hindsight. This prevents a prior forecast from being rewritten merely because the actual outcome is now known.

Control questions:

What condition existed at the prior reporting date?

What information was reasonably available when the prior disclosure was authorised?

What exactly does the new information demonstrate?

Would the revision use hindsight?

Metric changes are not all errors.

Redefined or replacement metric

Under B52, if an entity redefines or replaces a metric, it must:

disclose a revised comparative amount unless impracticable;

explain the change; and

explain why the redefined or replacement metric provides more useful information.

The rationale should be decision-usefulness, not easier data collection or a better trend. The metric dictionary and change request should show the old and new definition, boundary, formula, source, effect on trends and approval.

New metric

Under B53, a newly introduced metric requires a comparative amount unless impracticable.

A metric is not necessarily new because it appears in a new section or uses a revised label. Classify the substance. If the definition changed, B52 may be the relevant route.

Consistency over time

Paragraph 52 requires definitions and calculations, including target metrics, to remain consistent. Reconcile every current metric to the prior-year inventory and assign a status:

unchanged;

revised estimate under B50;

redefined;

replacement;

new;

discontinued because no longer material;

corrected error; or

comparative impracticable.

Paragraph 83 requires material prior-period errors to be corrected by restating comparative amounts unless impracticable. Paragraph 84 defines prior-period errors as omissions or misstatements arising from failure to use, or misuse of, reliable information that:

was available when the prior disclosure was authorised; and

could reasonably have been obtained and considered.

B56 gives examples including mathematical mistakes, mistakes applying metric or target definitions, oversight, misinterpretation of facts and fraud.

Paragraph 85 distinguishes corrections of errors from changes in estimates. Estimates are approximations revised as additional information becomes known.

Classification matrix

The assessment should be documented with technical accounting and assurance input where material.

Figure 2. Classify the event before deciding whether to provide, revise or restate a comparative amount. Original London Reporting Academy practitioner visual.

If a material prior-period error is identified, B58 requires disclosure of:

the nature of the error;

the correction for each prior period disclosed, to the extent practicable; and

if correction is impracticable, the circumstances and how and from when it has been corrected.

B59 says that when it is impracticable to determine the effect for all prior periods presented, the entity restates comparative information from the earliest practicable date.

An error correction should be linked to:

materiality analysis;

root cause;

corrected calculation or narrative;

effect on targets, trends and financial connections;

control remediation;

governance approval; and

assurance communication.

B54 explains that retrospective revision may be impracticable when data was not collected in a way that allows application of a new definition and cannot be recreated. If revising a comparative is impracticable, that fact must be disclosed.

Impracticability is a high threshold. It is not the same as:

expensive;

time-consuming;

requiring manual effort;

inconvenient for the reporting timetable; or

likely to produce an unfavourable result.

A defensible record shows every reasonable effort, the specific missing inputs, alternatives considered and why reconstruction cannot be achieved reliably.

Narrative information can change without any numeric restatement. The team should consider whether users need comparative context for changes in:

governance responsibilities;

risk appetite or risk process;

strategy and capital allocation;

materiality or aggregation conclusions;

value-chain scope;

time horizons;

scenario methods;

significant assumptions; and

policies, actions or targets.

For example, a new risk-management process should not be described as though it operated in the prior year. The disclosure should identify the change, effective date and implications.

Method changes that affect amounts require classification under B50-B53 or the error guidance. Method changes affecting narrative should still be explained where useful to understand comparability.

A controlled transition register should include one row for every quantitative amount, metric, target, financial-effect measure and significant narrative comparative decision.

Recommended fields:

record ID;

disclosure or metric;

UK SRS paragraph;

report location;

current-year information;

preceding-period information available;

comparative route and relief;

change classification;

prior-period condition test;

forward-looking metric test;

error materiality;

impracticability assessment;

required action;

quantitative effect;

disclosure wording;

evidence;

owner, reviewer and due date;

priority and status.

The downloadable workbook included with this Knowledge Card contains these fields, validation lists, a decision guide and a formula-driven dashboard.

Facts. A group disclosed 2026 water consumption as withdrawal minus discharge. In 2027, internal audit finds that discharge volumes from two sites were deducted twice. The source data and approved formula were available when the 2026 report was authorised.

Assessment. The issue is not new evidence about uncertain prior conditions. It is a calculation error. The group assesses materiality in the context of the sustainability disclosures.

Outcome. If material, the group restates the 2026 comparative, explains the nature and correction, reassesses target performance and remediates the calculation control. If immaterial, it corrects the current process and documents the materiality conclusion; aggregation with other errors is considered.

Limitation. This is an illustrative classification, not an error conclusion for a real entity.

Why it works: it identifies the relief, avoids implying that voluntary history is a full UK SRS comparative, and explains the baseline.

What must be adapted: standards applied, reporting period, any E3 use, voluntary historical information and regulatory route.

1. Assuming first-year relief means historical data is irrelevant

Correction: use history for baselines, estimates and future comparative readiness, while controlling voluntary disclosure.

2. Applying E1 and E3 without separating their effects

Correction: record the reporting route, claim consequences and climate/wider-sustainability timetable separately.

3. Calling every change a restatement

Correction: classify relief, estimate revision, method change, new metric and error before selecting language.

4. Rewriting a forecast with hindsight

Correction: apply B51 and preserve the information set and assumptions at the prior reporting date.

5. Changing a metric without explaining usefulness

Correction: meet B52 with revised comparatives where practicable and a decision-useful rationale.

6. Using “impracticable” for inconvenient reconstruction

Correction: retain evidence of every reasonable effort, alternatives and the specific inability to recreate data.

7. Correcting the table but not the connected narrative

Correction: update targets, trends, financial effects, commentary, internal controls and assurance evidence.

The package includes UK SRS S1 First-Year Transition Register 2026.xlsx, with:

a controlled transition register;

validation lists for reliefs, classifications and actions;

a comparative decision guide;

a dashboard; and

source and evidence fields.

It is a project tool, not a replacement for the final standard or an accounting judgement memo.