Match supplier data to the reporting boundary and period you requested
After the site-boundary reconciliation, a fictional Site A electricity example, kWh: 120,000 (January–December 2025) − 24,000 (January–March 2025) + 34,000 (January–March 2026) = 130,000 (April 2025–March 2026). The example covers purchased grid electricity through the same two incoming Site A meters, with no onsite generation, export or shared-meter allocation. Use the bridge only when measured records match the intended scope, unit and measurement basis without overlaps or gaps. The illustration assumes those records are available; it is not a proportional estimate or verification of a supplier return.
A supplier's response can contain useful records without answering the question you sent. Before copying a number into the reporting workbook, show the difference between the requested dataset and the returned one, then document any calculation that closes the gap.
This guide is for buyers reviewing incoming ESG data and suppliers explaining their records. It follows one fictional electricity response from a group calendar-year total to a supplying-site financial-year figure. The reconciliation is an optional review approach, not a prescribed reporting form.
Put the request beside the response
Keep the original response intact. In a separate working record, identify the request version and compare:
Who and where: the legal entity, supplying site and any named product or activity.
What: the metric definition, unit and whether the number is an absolute quantity, a ratio or a point-in-time count.
When: the requested start and end dates against the dates represented by the records.
How much is covered: included and excluded operations, meters, products or population groups.
How it was prepared: source references, measurement or estimation, calculation method and response version.
GHG Protocol's Supplier Engagement Guidance, pages 4–6, supports recording scope, period, sources, methods and uncertainties, then resolving data questions with suppliers. The workflow here applies that discipline to a received dataset. Other ESG topics still need their own definitions and reporting rules.
Do not edit the request to make it resemble the reply. If the business agrees to change the requested scope, record the change and its approval separately.
Choose a treatment for each mismatch
Extract or convert. Use a separately supported site subtotal, or convert a known unit. A conversion changes the unit; it does not repair the wrong site, missing months or a different metric.
Reconcile. Build the requested result from compatible components. Show what is retained, removed and added, with a source for every component. Check that the pieces neither overlap nor leave an unexplained gap.
Use a defined partial result. Preserve the supported quantity and label precisely what is absent. Keep the missing portion open for further evidence or a separately approved estimate.
Hold the value from this calculation. If identity, definition or coverage cannot be resolved, retain the response as evidence of the exchange without treating its number as an answer. Ask for the specific information needed to decide.
These are working decisions about data use, not supplier ratings. A return marked “response received” can still require reconciliation. Record the outcome in the supplier ESG response tracker and link the calculation evidence rather than recreating the tracker.
Worked example: resolve the site before the year
Every entity, record, number and review outcome below is fictional. The buyer requested Site A's purchased grid electricity for 1 April 2025 to 31 March 2026, in kWh. It requested the whole site's consumption, without allocation to the buyer's purchases. The agreed meter list contains two incoming meters; there is no on-site generation, export or shared-meter allocation in this simplified case.
The supplier first sends a group report showing 250 MWh for 1 January to 31 December 2025. Both the boundary and the period differ. The reviewer keeps the response open.
A follow-up returns a site schedule: Site A 120 MWh, Site B 100 MWh and the head office 30 MWh. For this example, the schedule covers the same electricity definition and calendar year as the group report, includes every group location and contains no overlapping consumption.
The boundary check is 120 + 100 + 30 = 250 MWh. The requested site's calendar-year subtotal is therefore 250 − 100 − 30 = 120 MWh, or 120,000 kWh. The reviewer retains the site schedule and its underlying meter references. The agreement of totals is a reconciliation check; it does not independently prove that the readings are correct.
If only the group total were available, dividing it by the number of sites would not establish Site A's consumption. An allocation would require its own supported basis and review. The Scope 3 Standard, chapter 8, advises avoiding or minimising allocation where possible and considering the relationship between activity and emissions when allocation is needed.
Build the period bridge from measured months
In this fictional case, the same two meters have complete, non-overlapping calendar-month records. The monthly totals agree to the supplier's site schedule; they represent consumption during those months, rather than merely invoices issued in them.
Remove January–March 2025: January 7,000 + February 8,000 + March 9,000 = 24,000 kWh.
Retain April–December 2025: the nine monthly records total 96,000 kWh. This equals 120,000 − 24,000.
Add January–March 2026: January 10,000 + February 11,000 + March 13,000 = 34,000 kWh.
Requested-period result: 120,000 − 24,000 + 34,000 = 130,000 kWh.
The result now covers Site A from 1 April 2025 to 31 March 2026. Save the month-level references beside the bridge. Each retained or added month enters once; excluded months stay visible in the reconciliation.
This works because the required observations exist. Two twelve-month totals for different years cannot simply be relabelled as interchangeable. For supplier data used in a Scope 3 Category 1 inventory, GHG Protocol recommends matching the inventory's time interval to the extent possible. Category 1 calculation guidance, printed pages 24–25
Keep a missing month visible
Suppose the March 2026 record has not yet arrived. The supported April 2025–February 2026 subtotal is 96,000 + 10,000 + 11,000 = 117,000 kWh. Save it as an eleven-month partial result. The full-year total remains unresolved.
Neither zero for March nor 117,000 × 12 ÷ 11 is a measured annual result. The latter assumes that a missing month resembles the observed average. If a reporting method permits estimation, document the reason, basis, uncertainty, reviewer and replacement plan; keep estimated and measured quantities distinguishable.
GHG Protocol permits suitable secondary or proxy data to fill Scope 3 gaps and recommends improving lower-quality inputs as better evidence becomes available. That does not establish that any particular extrapolation is suitable for this site. GHG Protocol guidance on data gaps and quality
When the fictional March record later supplies 13,000 kWh, update the bridge to 130,000 kWh and link the new response version to the superseded partial result. Do not add an old estimate again after replacing it.
Release only the conclusion the records support
The example establishes a matched electricity-activity figure under its stated assumptions. It does not calculate the buyer's emissions or a product footprint. Those uses need further method, boundary and any allocation decisions.
Matching labels and dates is also only part of review. For Scope 3 data, assess technology, time and geography, completeness and reliability, with quality sufficient for the inventory's purpose. A neatly reconciled file can still have uncertain underlying measurements. Scope 3 Standard, section 7.3
Before handing over the result, record:
The exact request and accepted response versions, including source locators.
The original value, each adjustment, final unit and reproduced calculation.
The remaining exclusions, missing periods and estimates, even if the exchange is administratively closed.
The permitted use of the result, reviewer, review date and next action for unresolved items.
Apply a period bridge only to a metric for which the pieces can legitimately be combined. Adding monthly point-in-time headcounts, for example, would not produce an annual headcount. Resolve that metric's definition before calculating.
Make the coverage explanation usable
Nitium's value-chain ESG reporting support helps organise partner responses, reporting coverage and evidence gaps within an agreed scope. Discuss a supplier-data reconciliation with the requested period and a non-confidential description of the mismatch.
Sources checked 13 October 2026. The GHG references are the 2011 Scope 3 Standard and Supplier Engagement Guidance, the 2013 Category 1 calculation guidance and the linked data-gap FAQ. This practical guide does not provide a legal opinion, certification or independent assurance conclusion.
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