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Cost control and budget deviations

📐 Article7 min read

Controlling costs is not recording deviations but anticipating them: the difference between the two is the moment the numbers are looked at. The useful system rests on three magnitudes, a classification by origin and an honest projection rule.

The dashboard's three magnitudes

Magnitude What it measures Compared against
Certified to date What has been executed and valued Budget and planned curve
Committed Contracts, orders and approved changes not yet certified The budget's remaining funds
Projection at completion Certified plus committed plus estimate of the rest Total budget with its provision

The certified looks at the past; the committed is the anticipation magnitude (a committed euro is spent even if not yet certified); the projection is the synthesis answering the only question that matters: where the project will end if nothing changes. The three magnitudes are presented together, since each answers a different question.

The classification by origin

Every deviation is labelled by cause, because each cause has its treatment:

Quantity. Execution differs from the design takeoff. It points back to the quantities: an origin error or a different real condition. In unit-rate contracts it is the structurally expected deviation and the one cumulative certificates detect effortlessly.

Price. New units (new rates) or agreed revisions. It is controlled through the construction rigour of each new price.

Scope. The design changed: these are change orders, and their control is decisional and documentary before it is arithmetic.

The labelling discipline has a side benefit: at each project's end, the deviation distribution by origin is the quality diagnosis of the process itself (many quantity deviations signal weak takeoffs; many scope ones, unstable briefs). That diagnosis only exists if the labelling is done during the works rather than at closure.

The projection rule and the actions

An honest projection incorporates the known bad news as soon as it is known: the probable change order, the new rate under negotiation, the chapter certifying above its curve. Projecting only what is signed produces the illusion of control that explodes in the final quarter.

Corrective actions follow the hierarchy of opportunity cost: first the decisions still open (unprocured specifications, execution alternatives in chapters not yet started), then negotiating what is committed, and only at the end scope cuts, decided with the client and in writing. The contingency provision is consumed against recorded causes, never as a diffuse cushion.

The essentials

Cost control is a triangle (certified, committed, projection) with a classification by origin (quantity, price, scope) and one rule: project the known bad news immediately. With a monthly review anchored to the certificate, the system anticipates; without the committed and without an honest projection, it merely documents the deterioration.

Note: usual practices in Spain in 2026; thresholds and frequencies are adapted to each project.

Frequently asked questions

Certified, committed and projection to completion. Each answers a different question and all three are presented together.

Because a committed euro is spent even if not certified. Watching only the certified amount is driving by the rear view mirror.

By origin: quantity, price, scope and time. The final distribution by origin is the quality diagnosis of the design process itself.

As soon as the projection picks it up, not at closure. A deviation found late no longer admits correction, only recording.

Quantities and budgets in Spanish construction: complete guide