A Problem Every Group CFO Knows
The dashboard shows a gross margin of 38% for the North subsidiary and 29% for the South subsidiary. A nine-point gap. The board wants an explanation by Thursday. And all you have right now is a number in a box.
This is precisely where Power BI reveals its true value — or its limitations, depending on how the model was built. Good multi-entity financial reporting doesn't just display KPIs: it must allow you to move from summary to granular, identify the source of the gap, and verify that the calculation rules applied to each entity are genuinely comparable.
This article sets out a structured method for doing that work — from reading the KPI to the underlying accounting entry, through the three most common friction zones: calculation rules, currencies, and scope.
Step 1 — Read the Gap Before Explaining It
The first mistake is jumping to a conclusion. Before explaining a gap, you need to qualify it: is it structural or one-off? Stable over time or did it appear this month? Present across all product lines or concentrated on a single family?
Power BI allows you to answer these questions in a few clicks, provided the data model is correctly structured with hierarchies. Drill-down navigation — moving level by level through a hierarchy (group → subsidiary → product family → product) — lets you locate the anomaly without rebuilding an analysis in Excel. Best practice in BI converges on the same logic: a good dashboard tells a story — current situation, trend, gap, recommended action.
In practice, the first read should answer three simple questions: over what period did the gap appear? On which product lines is it concentrated? Does it have a visible counterpart in costs, or only in revenue?
Step 2 — Verify That Calculation Rules Are Identical Across Entities
A margin gap between two subsidiaries is not always a performance gap. It is often a methodology gap. Before drawing any economic conclusion, the CFO must confirm that both entities apply the same calculation rules.
The three most frequent divergences are as follows.
The first concerns the numerator of the margin — that is, what is called "gross profit." Some subsidiaries include commercial discounts in this figure, others do not. Some deduct transport costs, others classify them as operating expenses. Without a documented common framework, the comparison is meaningless. Applying a shared reference framework is the prerequisite for aligning accounting methods and presentation across entities.
The second concerns the denominator — the revenue figure used. Invoiced? Collected? Net of credit notes? A subsidiary that records its credit notes in the following month will mechanically show a higher margin at period end.
The third concerns analytical allocations. Costs recharged by the holding company, shared services allocated using different keys: all of these inflate or reduce an entity's margin without reflecting its actual performance.
In Power BI, controlling these rules means documenting the DAX measures used for each entity. Best practice is to define each KPI once as a centralised measure, applied uniformly across all entities. If different measures coexist for the same indicator, the displayed gap is first and foremost a modelling artefact.
Step 3 — Handle Currencies Correctly
As soon as a group includes subsidiaries that invoice in different currencies, exchange rate management becomes an invisible source of variance. A subsidiary whose functional currency has appreciated by 5% over the quarter may show a higher margin without having sold a single additional unit.
Multi-currency reporting in Power BI works by separating the storage of transactions from their presentation: all source data remains in the entity's functional currency, and a DAX conversion layer applies the correct exchange rate at the point of calculation.
Three questions must be documented and verifiable in the model: which rate is applied — closing rate, average period rate, or budgeted rate? Are rates updated automatically or entered manually? And are translation differences isolated on a dedicated line or absorbed into the margin?
Without clear answers to these three questions, comparing the margin of two subsidiaries denominated in different currencies is comparing apples and oranges.
Step 4 — Verify Scope: What Goes Into Each Entity's Calculation
Scope is the third friction zone. Two configurations are particularly common in mid-sized groups.
The first is the uneliminated intercompany flow. If the North subsidiary sells products to the South subsidiary, and these flows are not correctly eliminated in the consolidated reporting, the group's margin will be artificially inflated. The trial balance is the foundation of any reliable consolidation, and all adjustments must be reconcilable back to it.
The second is the consolidation scope itself. Does a subsidiary acquired mid-year enter the calculation for the full year, or only from the acquisition date? Is a subsidiary divested mid-year retroactively excluded? These questions of temporal scope produce base effects that can explain several points of variance with no operational divergence whatsoever.
In Power BI, verifying scope means applying explicit filters on the entities included in each calculation, with documented records of scope entries and exits.
Step 5 — Trace Back to the Entry
Once the three friction zones have been checked — calculation rules, currencies, scope — if the gap persists, you need to trace back to the source entries. This is the final step, and often the most revealing.
In a well-structured analysis, two accounts typically represent 80% of a gap. The analysis can move from macro to micro in two clicks. In Power BI, this navigation uses drill-through: right-clicking on the relevant KPI opens a dedicated page for the entity, where the underlying entries are visible with their description, date, account, and amount.
This is where financial reporting meets management accounting. And this is where the controller or CFO can say, with evidence: the margin gap between the two subsidiaries is explained X% by a difference in discount calculation rules, and Y% by an uneliminated intercompany flow.
What This Means for Model Design
This five-step method is not a one-off exercise — it is a design requirement. For it to be practical, the Power BI model must have been built from the outset with the right foundations.
The golden rule of successful financial BI projects: harmonise the chart of accounts and reference data before connecting Power BI — without this, the tool amplifies source errors rather than correcting them. The mapping and harmonisation phase typically represents 30 to 50% of total project time.
Concretely, this means a common chart of accounts across subsidiaries, centralised and documented DAX measures, an automatically updated exchange rate table, and navigation hierarchies built to allow drill-down to the entry level.
Once this foundation is in place, monthly reporting refresh time can drop from several days to a few minutes. And above all, the CFO can answer the board's question — not with an impression, but with a demonstration.
How Trevys Can Help
Trevys supports group finance teams in structuring their Power BI reporting — from source mapping to DAX measure design and model governance. If your dashboards are showing gaps you can't yet explain, it is usually a question of foundation, not numbers.