An assurance budget can include the provider’s fee, time spent preparing evidence and the work needed to resolve questions. Comparing prices becomes difficult when a figure covers a complete sustainability statement and another covers selected indicators.
ESG assurance and audit cost statistics are most useful when their scope stays attached to the number. Published company fees show what particular engagements cost. Research samples reveal differences between groups. Economic models estimate how costs might change under different requirements.
For budget planning, identify which category a benchmark belongs to before using it. The broader breakdown of ESG reporting costs covers the surrounding investment in people, systems and specialist support. Assurance-specific evidence helps assess the engagement and its preparation work more closely.
ESG assurance and audit cost statistics at a glance
The table summarises 4 headline findings. Keep the period, currency and engagement scope attached to each figure when quoting it.
| Finding | What it measures | Period and source |
|---|---|---|
| Philips disclosed €1.3 million for sustainability assurance | Separately identified provider fee | Financial year 2025, Philips annual report |
| AstraZeneca disclosed US$2.8 million for sustainability assurance | Separately identified provider fee | Financial year 2025, AstraZeneca annual report |
| Great Portland Estates disclosed £73,000 for sustainability assurance | Separately identified provider fee | Year ended March 2025, annual report, page 161 |
| External assurance fees were projected to fall by about 20% | Modelled change under revised ESRS against the ESRS 2023 baseline | European Commission staff working document, 2026 |
Benchmarking tip: The currencies and engagement scopes differ. These figures do not form a comparable price range or an average quote for another business.
What companies disclose about sustainability assurance fees
Annual reports can provide concrete fee evidence, especially when sustainability assurance appears as a separate line. They also show why a financial audit fee, an audit-related services total and a sustainability assurance fee need different labels.
Philips disclosed €1.3 million for sustainability assurance
Philips separately identified €1.3 million for sustainability assurance in its 2025 audit and audit-related fees table. Its sustainability statement received limited assurance, with reasonable assurance over specified additional disclosures and metrics.
That combination matters when interpreting the fee. An engagement covering an entire statement and additional work over selected metrics cannot be compared directly with a narrowly scoped review of energy consumption.
For an internal comparison, prepare a scope sheet identifying the entities, topics, assurance levels and period covered. A structured assurance data room can then organise the evidence around that agreed perimeter, so both the provider and company contributors understand the expected work.
AstraZeneca disclosed US$2.8 million for sustainability assurance
AstraZeneca’s 2025 annual report identified US$2.8 million payable to KPMG for sustainability assurance. It separately identified subsidiary audit work and other assurance services.
This separation makes the disclosure useful for research. It allows a reader to identify the sustainability engagement without combining all services from the same accounting firm into the same cost category.
Companies can use the same discipline internally by distinguishing the independent engagement from advisory support, data preparation and financial audit work. Coordination between finance and sustainability teams helps ensure that purchase orders, budgets and service descriptions use consistent categories.
Great Portland Estates disclosed £73,000 for sustainability assurance
Great Portland Estates reported £73,000 for sustainability assurance for the year ended 31 March 2025. Its annual report describes assurance activities concerning selected sustainability disclosures.
The disclosure illustrates how an engagement with a defined selection of indicators can sit alongside a broader annual-report audit. The amount should be interpreted with the selected disclosures and accompanying assurance statement.
For companies comparing carbon footprint audit solutions, check how each option supports evidence preparation and external review. Look for traceable calculations, accessible source documents and clear records of which sites and emissions scopes are included.
How Dcycle supports assurance preparation
An assurance provider may request an invoice, a calculation, an explanation of the reporting boundary and evidence of review for the same figure. When those items sit in different systems, answering a sample can involve several people and repeated searches.
Dcycle is an environmental data platform that connects operational records with calculations, supporting documents and review workflows. The same information can support assurance preparation, reporting, cost analysis and operational decisions. Independent practitioners remain responsible for their assurance procedures and conclusions.
Bring source records into a consistent structure
When comparing ESG data collection software, check whether it can organise invoices, spreadsheets and connected records by activity, site and period. Each figure should remain linked to its original source so the team can retrieve supporting evidence during assurance reviews.
For example, the finance team may already hold the energy invoices needed for an emissions calculation. Reviewing the available system integrations establishes which records can flow from existing systems and which need a controlled upload process.
Connect reported figures with supporting evidence
Dcycle’s evidence and traceability capabilities connect data points with source records and their processing history. Teams can retain the documents and calculation context needed to explain a result.
If a reviewer selects a fuel-consumption figure, the preparer can work from the associated records and methodology. Any gap becomes a specific question about a document, assumption or transformation, making it easier to assign the follow-up.
Organise responsibilities across sites and entities
Roles and permissions support defined access and responsibilities. Multi-entity management helps organise information across subsidiaries and facilities before consolidation.
This is useful when a group figure includes records supplied by several local teams. Naming the contributor and reviewer for each activity gives the central team a clear route for resolving missing evidence or inconsistent submissions.
Maintain information for the next review cycle
Through multi-framework reporting, collected information can support different outputs while retaining its underlying context. Teams still need to assess whether the boundary, method and period meet each output’s requirements.
A corrected electricity record may affect an emissions calculation, a customer response and an internal site comparison. Keeping the source and calculation together helps the company assess those effects without rebuilding the record for every use.
How assurance fees differ across sectors and company sizes
A 2026 study in Meditari Accountancy Research analysed financial-year 2024 data from listed European companies.
Financial institutions paid mean fees of €2.63 million
Mean sustainability assurance fees were €2.63 million for financial institutions disclosing fees.
When using a sector benchmark, compare the activities being assured. A financial institution’s information needs may involve a different mix of operations, estimates and counterparties from those of a manufacturer or property business.
For finance teams managing environmental information, a practical comparison should identify which indicators need specialist methods and which depend on routine records. That distinction helps explain the work behind a proposal.
Non-financial companies paid mean fees of €690,000
The corresponding mean for non-financial companies disclosing fees was €690,000.
A mean can be influenced by large engagements. It also says little about the fee a company with a smaller perimeter or better-prepared evidence should expect. Detailed proposals remain necessary for procurement decisions.
Use consistent data collection practices to describe the information available to the provider. A proposal based on documented sources and established methods is easier to assess than one built around unresolved assumptions about data availability.
Relative fees ranged from 30–43% for smaller firms to 1–5% for larger firms
Assurance fees represented 30–43% of financial audit fees for smaller groups and 1–5% for larger groups.
The smaller firms should not be relabelled as SMEs. The public abstract does not provide the detailed group thresholds. The ratios also depend on the financial audit fee used as the denominator.
For internal analysis, examine the absolute assurance fee alongside the ratio. Clear governance and ownership can help explain whether the proposed work reflects the engagement’s scope, new information or preparation tasks that still lack an owner.
Why published fee benchmarks remain incomplete
The same study found uneven fee disclosure. For procurement teams, missing observations are a reason to examine how a benchmark was assembled before using it.
Separate fees were disclosed by only 93 of 263 companies
Separate sustainability assurance fees were available for 93 of the 263 companies studied.
Missing disclosure does not establish that a company obtained no assurance or paid no fee. The amount may be included in a broader services category that cannot be reliably separated using the published information.
For finance teams, this is a reason to request the definition behind any external benchmark. A research sample assembled from visible fees may differ materially from the company’s own engagement and operating model.
Separate disclosure reached 73.8% among French companies
Separate fee disclosure reached 73.8% among the French companies studied.
Greater visibility makes research easier, but does not make every engagement comparable. A fee table still needs to be read alongside the service description, reporting perimeter and assurance statement.
When recording peer information, preserve a short note explaining what the amount includes. That note is particularly important if a fee covers several assurance levels, reporting outputs or periods of work.
The comparable disclosure rate was 13.0% in Germany
The corresponding separate disclosure rate for German companies was 13.0%.
It cannot support a conclusion that German companies generally buy less assurance or pay lower fees. Those questions require evidence about engagement coverage and amounts that the disclosure rate alone does not provide.
A practical research file should mark undisclosed amounts as unavailable. Recording a zero would distort an average, while assigning the full audit-related services total to sustainability assurance could overstate the cost.
What 3 cost models suggest about future assurance spending
The European Commission’s 2026 analysis models revised ESRS costs against the ESRS 2023 baseline. Its projections are planning estimates, not observed company savings.
1. Assurance represented roughly 40% to over 50% of modelled reporting costs
Under the baseline, assurance represented roughly 40% to over 50% of total reporting costs. This category combined external assurance fees with internal work supporting the engagement.
That definition is essential. A cost share including employee preparation time cannot be compared directly with an annual report’s separately disclosed provider fee.
Map the internal work by department, including document preparation, calculation review and responses to samples. A clear view of departmental data responsibilities helps capture effort that may otherwise disappear inside finance, operations or sustainability budgets.
2. External assurance fees were projected to fall by about 20%
External assurance fees were projected to fall by approximately 20% under revised ESRS.
For procurement, assess what would actually change in the proposed engagement. Fewer applicable disclosures, clearer calculation criteria or a narrower perimeter may alter the work, but the effect needs to be reflected in a provider’s proposal.
When assessing automated CSRD processes, measure the specific preparation tasks affected. Faster document retrieval and more consistent calculations can be tracked internally without assuming that the same percentage will appear on the assurance invoice.
3. Internal support costs were projected to fall by 24% and 15%
Modelled internal assurance-support costs fell by 24% for smaller companies and 15% for larger companies.
Track this work using comparable categories across cycles. Record time spent retrieving evidence, explaining estimates, resolving inconsistencies and approving corrections. Changes in scope should be documented alongside changes in hours.
Maintaining environmental information for financial analysis gives the preparation work additional uses. Reviewed consumption and purchasing records can support cost investigations and investment decisions as well as the annual assurance process.
How to compare assurance proposals using these statistics
Start with the engagement description. Identify the reporting framework, assurance level, entities, locations, indicators and period. Ask how the provider will handle changes in scope, additional testing and unresolved evidence gaps.
The IAASB publishes separate extracts for limited and reasonable assurance engagements. The distinction should be explicit in a proposal. A practical explanation of verification and assurance can also help internal contributors understand what the engagement covers.
Next, identify the assumptions about company preparation. Ask which schedules, reconciliations and source documents must be ready before fieldwork. Allocate review responsibilities early and document decisions about double materiality where relevant to the reporting perimeter.
Keep operational improvements measurable. Evidence on reporting automation can inform a project, but the company’s own measures should include retrieval time, correction volumes and unresolved requests. Those results explain whether a change has improved preparation.
Review proposed additional charges before signing. Establish who approves extra work, how the provider records it and whether travel or specialist services sit outside the quoted fee. After completion, compare the final invoice with the original assumptions. Documenting the reasons for any difference gives the next tender a more reliable starting point.
Methodology and limits of the cost evidence
The company examples are individual disclosures in their original currencies. They have not been converted into a shared currency or used to calculate a market average. The periods, providers and assurance scopes differ.
The listed-company findings come from the study’s public abstract. Subgroup counts and size thresholds are unavailable there. The Commission figures are modelled estimates with their own baseline and cost definitions.
When citing a finding, retain its unit and denominator. A provider fee, a share of financial audit fees, a country disclosure rate and a projected reduction in internal effort answer different questions.
Give the assurance budget a clear scope
Use published statistics to challenge assumptions and identify questions for providers. Then build the budget around the actual engagement, the evidence available and the internal work required to support it.
Dcycle helps teams connect environmental records, calculations and review history so the same information supports assurance preparation, reporting, cost analysis and operational decisions. To examine the workflow using existing records and systems, request a demo.
Connect source records, calculations, evidence and reviews in a governed environmental data workflow.
See Dcycle in actionFrequently asked questions (FAQs)
What is the average cost of ESG assurance?
The evidence above does not establish a universal average. Published fees concern different companies and engagement scopes, while research means apply to defined samples.
For a useful estimate, specify the information being assured, the assurance level, the company perimeter and the preparation expected from staff. Request proposals on that same basis.
Is sustainability assurance included in the financial audit fee?
Fee disclosures use different categories. Some identify sustainability assurance separately, while others include it within a wider audit-related or assurance services total.
Read the accompanying notes before assigning a cost. For internal records, maintain a separate service description so that financial audit work, sustainability assurance and advisory support can be distinguished.
Do smaller companies always pay less for assurance?
Company size alone does not establish the work required. The evidence also distinguishes absolute fees from fees expressed as a share of financial audit costs.
Compare the perimeter, information complexity, assurance level and evidence available. A smaller organisation with fragmented records may still need substantial preparation and specialist support.
Can software guarantee a lower assurance fee?
Software can help organise records, calculations and evidence. The provider determines the procedures and fee for the agreed engagement, considering its scope and risks.
Measure software’s effect on identifiable tasks, such as retrieving documents and resolving inconsistencies. Discuss any resulting change in the expected assurance work with the provider.
What should an assurance budget include besides the external fee?
Include staff time preparing evidence, reviewing calculations, answering requests and correcting information. Identify any separately commissioned methodology or technical support.
Keep these activities distinct from the provider’s engagement so costs can be reviewed after completion. Recording the same categories in the following cycle makes comparisons more useful.
