Use this diagnostic before a margin bridge is needed
Cost creep starts with repeated input-level exceptions: a supplier unit rate edges upward, pack size changes, usage per job drifts, a fee appears on more statements or an allocation base no longer matches activity. The purpose is early detection and ownership, even when the total profit layer has not yet moved enough to justify a full margin-compression bridge.
Build a stable comparison key for each input—supplier and item, unit of measure, currency, tax treatment and effective date. Comparing invoice totals alone can confuse a higher quantity with a higher unit rate. Comparing percentages alone can hide a small per-unit change that repeats across thousands of units.
Detect, reconcile and assign cost movement
Prerequisites, sequence and checkpoints
- Freeze a comparable baseline with the same period, scope, volume unit and tax basis. (not complete)
- Collect price, quantity, mix, usage, waste, fee and allocation records. (not complete)
- Build signed bridge rows and reconcile them to the total cost change. (not complete)
- Investigate the residual and separate evidence from possible explanations. (not complete)
- Assign one next action, owner and data-based review trigger. (not complete)
Separate bridge drivers before action
| Driver | Evidence | Potential owner action |
|---|---|---|
| Rate | Matched supplier or service unit rates | Renegotiate, redesign or reprice scenario |
| Quantity/mix | Matched output and input quantities | Process or mix review |
| Waste/fees/allocation | Usage, return, statement and pool records | Operational or basis review |
Reconcile a fictional cost bridge
Reproducible user scenario
One monthly, tax-excluded CU example with no benchmark threshold.
| Step | Input or arithmetic | Decision meaning |
|---|---|---|
| Total change | Current 52,400 - baseline 50,000 = +2,400 CU | Bridge target |
| Explained | Rate +900; quantity +700; mix +300; waste +250; fees +150 = +2,300 CU | Supported subtotal |
| Residual | 2,400 - 2,300 = 100 CU | Keep visible until rounding or records explain it |
Produce an exception register, not a second margin diagnosis
| Validated signal | First owner and action | Escalate when |
|---|---|---|
| Supplier rate changed on a matched unit | Purchasing: verify effective date, credit and alternative | Repeated impact exceeds the business-defined review tolerance |
| Usage or waste rose at an unchanged rate | Operations: inspect process, yield and specification | The change persists across a comparable run or job set |
| New fee or surcharge appears | Channel/account owner: verify contract and incidence | The fee is recurring or changes channel contribution materially |
| Allocation rate moved but pool did not | Finance/operations: review denominator and idle capacity | Object decisions reverse under a reasonable alternative basis |
Escalate from this register to the margin-compression diagnostic only when the validated exceptions need to be reconciled with price, sales mix and a named profit-layer change. Until then, keep the output at input level so the responsible team can act without inventing a business-wide cause.
Limitations, evidence and next action
Use the calculation owner for the next step
- Supplier Cost Increase Impact Planner
Respond to a supplier cost increase
- Gross to Operating Profit Bridge
Identify which operating-cost layer changes profit after gross profit
Questions and boundaries
- What percentage should trigger action?
- No universal threshold is supplied. Set a trigger from your decision tolerance, data quality and review cost.
- Is the residual a mistake?
- Possibly, but it can also be rounding, timing, missing records or a driver not yet modelled.
Sources and scope
- Basic cost behaviour patterns — OpenStax: Supports fixed, variable and mixed-cost concepts within a stated activity range.
- Choose a pricing strategy — business.gov.au: Stable pricing decision concepts only; no Australian rule or value is treated as global.