Indexed contracts: test the lag between costs and repricing
An indexed sales contract can pass through only part of an input-cost increase, and can do so after a delay. A statement that revenue is inflation-linked does not establish immediate margin protection. Rebuild the actual index formula, observation date, reset date and limits before estimating the operating effect.
Read the index clause precisely
The BLS PPI price-adjustment guide discusses choosing the index, reference period, adjustment interval and published-data version for a contract clause. It does not write the contract or determine how a dispute should be resolved. The formula below is hypothetical and should not be treated as a BLS-recommended commercial term.
Copy the index identifier and title, seasonal-adjustment status, base observation, reset frequency, publication lag, cap, floor and indexed weight. A broad inflation series can differ from the supplier’s actual input basket. Also distinguish a formula that adjusts price from the original base from one that compounds each period’s permitted change.
A hypothetical partial-index formula
Assume a fictional contract sets price as P = 100 × [0.40 + 0.60 × (I / 100)]. Forty percent is fixed; 60% follows the chosen index. When the index rises from 100 to 120, the formula price becomes 112, a 12% increase, not 20%.
Assume the initial unit cost consists of 60 of the indexed input and 20 of other cost, giving contribution of 20 at price 100. The input cost rises 20% to 72 on January 1, while other cost remains 20. The contract resets only on July 1 and caps the permitted price increase at 8%.
| Hypothetical period | Unit price | Unit cost | Contribution |
|---|---|---|---|
| Before input increase | 100 | 80 | 20 |
| January–June, before reset | 100 | 92 | 8 |
| July–December, capped reset | 108 | 92 | 16 |
The uncapped reset price would be 112, restoring the simplified 20 contribution. The actual assumed cap leaves four unrecovered per unit after July. The first-half lag exposes the business to the full twelve-unit input increase before any repricing.
Reconcile the annual consequence
Assume 1,000 units are delivered in each month. Annual contribution is 6,000 × 8 + 6,000 × 16 = 144,000. At the original contribution of 20 on the same 12,000 units, it would have been 240,000. The 96,000 gap comprises 72,000 from the first-half lag and 24,000 from the second-half cap under these assumptions.
This example holds volume, quality, other costs and collection unchanged. It does not forecast actual company margins. A real contract can have carryforward provisions, cumulative caps or renegotiation rights that change later recovery. Preserve those terms rather than assuming that every unrecovered amount is permanently lost.
Match the observed index to billing
A January index may be published later and revised afterward. The applicable contract might require a first-published, interim or final value. Record the version actually used in the bill rather than replacing it silently with the newest statistical observation.
Review when input costs move before a reset, the cap binds, the referenced series is discontinued, or the supplier’s basket diverges from the index. The next check should be the affected clause and billing period. A favorable general PPI movement is not proof that the company has already repriced its customers.
Define the research output
Create a pricing calendar with base price, indexed share, reference values, publication dates, reset dates, limits and actual invoices where available. Maintain a separate cost calendar for the underlying purchases. Their overlap explains exposure during the lag, rather than a single annual inflation percentage.
Public filings may summarize a clause without its detailed formula. Use a range for unknown weight or timing and avoid claiming exact pass-through. This task tests a contractual repricing mechanism, not merely a retrospective gross-margin bridge or a legal interpretation of undisclosed terms.
FAQ
Does a 20% index increase raise every indexed price by 20%?
No. The indexed weight, cap, reset convention and other terms determine the change. Reproduce the actual formula before applying a percentage.
Should revised index data replace the original billing value?
Only if the contract requires that treatment. Preserve the data vintage and calculation originally used, then show any contractual true-up separately.