What a cost index is, how to bring an old estimate to today's price level, and the three escalation routes every works office deals with — labour (10C), specified materials (10CA) and quarterly index-based escalation (10CC) — with the records each claim must stand on.
One number that carries a whole schedule of rates forward in time.
A schedule of rates is priced at a particular point in time — its base. Prices of labour, cement, steel and carriage do not stay there, so the organisation publishes a cost index: a number that says how far the general price level has moved since the base. If the base is taken as 100 and the current published index is 132, the price level is treated as 32% above the base. The index is a blended figure — it is built from the weightages of labour and key materials in typical works, so it moves more steadily than any single material price.
The everyday use in an estimating office is updating an old estimate. A preliminary estimate framed two years ago on old rates need not be re-worked item by item for an administrative approval today — you scale it:
Illustrative: an estimate of ₹48.00 lakh framed when the index stood at 114, updated when the index reads 129, becomes 48.00 × 129 ÷ 114 ≈ ₹54.32 lakh. The same one-line arithmetic is available as a quick utility on our converters & utilities page.
Keep two habits: always record which index series and which base you used on the face of the estimate, and never mix indices from two different series in one calculation — a scaling is only as honest as the pair of numbers behind it.
Escalation is not one thing. Works contracts provide three distinct routes, each with its own trigger, its own measure and its own paperwork. A running account bill may carry claims under more than one of them at the same time — they compensate different costs and do not overlap.
| Route | Compensates | Trigger | Measured on | Direction |
|---|---|---|---|---|
| Clause 10C — labour | Wage cost forced up by law | Statutory revision of minimum wages after receipt of tenders | Man-days worked out from the rate analysis of items actually executed after the revision | Payment only (a statute rarely lowers wages) |
| Clause 10CA — specified materials | Price movement of listed materials | Published price of a listed material (cement, steel and the like) differs from its base price | Consumption of the listed material derived from executed quantities × consumption norms | Both ways — extra payment on rise, recovery on fall |
| Clause 10CC — index-based | General price rise over a long contract | Contract period (with extensions where admissible) runs beyond the exempt initial period | Value of work done each quarter, adjusted for advances and departmental material | Both ways, following the index |
Trigger: the appropriate government notifies a revision of minimum wages after the tenders were received. The contractor's labour now costs more by force of law, and the clause reimburses that statutory increase — not market wage drift.
The man-days come from the rate analysis of the executed items: each item's analysis carries labour coefficients (mason, mate, coolie…) per unit; multiply by the quantity executed in the affected period and you have the man-days that the wage rise touched.
Trigger: the published price of a material listed in the contract schedule — typically cement and reinforcement steel — moves away from the base price named in the contract. Only listed materials qualify; everything else is deemed covered by the quoted rates.
Two masters do the work: a price master (base price and the published price for each period) and consumption norms that convert executed item quantities into tonnes of cement or steel for the bill period.
Trigger: long-duration contracts where the clause applies. Instead of chasing individual wage notifications or price circulars, it compensates general inflation using published indices, settled quarter by quarter, usually after an initial exempt period.
Road and infrastructure contracts usually state 10CC the long way: a per-component fold over the weightages printed in the contract's Schedule F. It reduces to the same idea as above — pay escalation on what the contractor financed, in proportion to how each input's index moved — but the anatomy is worth knowing, because audit objections live in the steps.
Each component of the work — typically Cement · Labour · Civil Materials · E&M · Diesel/POL · Steel · Bitumen — carries its own published index and its own weightage. A component whose index hasn't moved contributes nothing; one that fell contributes negative escalation, and the clause works both ways.
During the construction period all components participate. During the maintenance period the consumable inputs — cement, steel and diesel — drop out of the fold, because maintenance work doesn't consume them at construction-period scale; escalation there rides on labour, civil materials, E&M and bitumen only.
Our article works one escalation claim end to end — from trigger to the entry in the RA bill — and shows where each record slots in.