Introduction
There is a version of commercial management that is essentially archaeology.
You dig through the records each month, piece together what happened, report a number, and move on. The CVR reflects the past. Decisions happen in response to what has already gone wrong.
And then there is a version where the CVR tells you where the project is going, not just where it has been. Where you can see a margin problem forming in month three and act on it, rather than explaining it at the final account review.
The difference between the two is how you use your CVR data to forecast project outturn.
Outturn forecasting is not a separate discipline from CVR management. It is the most important output of it. Every CVR should produce a forecast of the final financial position, and that forecast should be specific, current, and treated as a management tool rather than a number to be filed.
This article covers how to build a reliable outturn forecast from CVR data, what the most common errors are, and what the forecast should actually drive in terms of commercial action.
What Project Outturn Means
Project outturn is the final financial outcome of a construction project. Specifically, it is the difference between the total final cost of the project and the total final certified value, which equals the final margin.
Forecast outturn, or projected final account, is what your commercial team believes the final margin will be based on the current position and the best available information about how the project will complete.
A reliable forecast outturn should answer three questions:
- What will this project cost in total by the time it is complete?
- What will this project earn in total by the time the final account is settled?
- What margin will be left, and is it consistent with the tender allowance?
The earlier you can answer these questions with confidence, the more options you have to influence the outcome.
Why Outturn Forecasting Fails in Practice
Most commercial teams produce a forecast final account as part of their CVR. Very few of them find it genuinely reliable by the time the project closes. Here is why.
The Forecast Is Built from Incomplete Data
A forecast final cost is only as good as the cost data behind it. If subcontract packages have not been assessed to final value, if procurement commitments are not captured, if variation costs are tracked informally, the forecast final cost will understate the true position.
The same applies to forecast final value. If upstream variations are included at full submitted value without assessing the probability of recovery, the forecast value is optimistic. If anticipated variations are not included at all because they are not yet instructed, the forecast is incomplete.
It Is Only Updated Once a Month
Monthly CVRs mean monthly outturn forecasts. On a fast-moving project, a lot can change in four weeks. Cost overruns on a package, a variation instructed late in the month, a certification that came in below expectation. None of these appear in the forecast until the next period end.
For commercial directors trying to manage across a portfolio of projects, a forecast that is potentially four weeks out of date is difficult to act on confidently.
The Numbers Move but the Narrative Does Not
A forecast that changes each month without explanation is not a forecast. It is a moving target.
When the projected final margin on a project drops by three points between two consecutive CVRs, the question that matters is why. What changed? What is driving the movement? Is it a one-off adjustment or a trend?
Forecasts that report the number without explaining the movement cannot drive the right commercial decisions.
How to Build a Reliable Outturn Forecast
A reliable outturn forecast is built from five components, each of which requires specific discipline to maintain accurately.
1. Committed Costs to Complete
Start with the total committed cost on the project: all subcontract orders, all purchase orders, all labour commitments. This is the floor for your final cost, assuming nothing else goes wrong.
For each subcontract package, assess whether the current order value is sufficient to complete the remaining works. If a package is trending over order value, the forecast should reflect the anticipated final subcontract cost, not just the order value.
RICS guidance on cost reporting emphasises the importance of distinguishing between committed costs and the assessed final cost on each package. These are different figures, and confusing them is a common source of forecast error.
2. Uncommitted Costs to Complete
What work remains to be procured or placed? Preliminaries for the remainder of the programme. Any packages not yet let. Likely additional direct costs.
Uncommitted costs are estimates. But they need to be included in the forecast or the final cost will always come in higher than projected. A forecast that only captures committed costs is not a forecast of the final position.
3. Variation Cost Assessment
Every downstream variation should be assessed and included in the forecast final cost. This includes instructed and valued variations, instructed but unvalued variations (estimated at the likely final value), and anticipated variations where there is reasonable expectation they will be instructed.
Carrying only approved variation costs in the forecast produces a misleadingly low final cost. The discipline is to include anticipated cost with appropriate risk weighting rather than waiting for formal instruction.
4. Forecast Final Value
The value side of the forecast runs through the contracted sum plus all variations upstream.
Approved upstream variations can be carried at face value. Submitted but unapproved variations should be assessed for likely recovery. A variation submitted at £80,000 that has been sitting with the client for three months with no response carries a different probability of full recovery than one submitted last week.
Anticipated variations that have not yet been submitted should be included at a probability-weighted value if there is reasonable expectation of entitlement.
5. Risk Allowance
Every outturn forecast should carry an explicit risk allowance: a sum of money set aside for cost items that are possible but not yet certain. Subcontract disputes. Delayed completion costs. Unresolved scope gaps. Claims from subcontractors.
The risk allowance should be based on a real assessment of the project risks, not a percentage added mechanically. It should be reviewed and updated each month as risks crystallise or are resolved.
What the Forecast Should Drive
The outturn forecast is not a reporting exercise. It is a decision-making tool. Here is what it should be driving.
Package by package action. If the forecast shows a specific subcontract package trending £50,000 over order value, the commercial action is to investigate why and what can be recovered. The forecast should identify the problem precisely enough to point to the action.
Variation recovery. If the value side of the forecast is carrying £120,000 of submitted but unapproved upstream variations, those variations need to be actively progressed with the client. They are value at risk. The forecast makes that visible; the commercial action is to chase them.
Subcontract final account strategy. If the forecast shows a subcontract package where the likely final cost is materially above the current agreed position, that gap needs to be managed before the subcontractor's final account submission. Addressing it early gives you more options.
Commercial director decisions. At portfolio level, the outturn forecast allows a commercial director to see which projects are on track, which are under pressure, and where management attention needs to be directed. That is only possible if the forecast is accurate and current enough to be trusted.
StoneRise's commercial management software connects variation tracking, subcontract management, and CVR reporting in one system, so the outturn forecast is built from live data rather than manually assembled spreadsheet entries. Read more about how CVR connects to the final account in our article on CVR vs final account in construction.
Conclusion
Forecasting project outturn is not about predicting the future with certainty. It is about giving your commercial team the clearest possible picture of where the project is heading, early enough to do something about it.
That requires complete cost data, a realistic assessment of variation recovery on both sides, an honest view of uncommitted costs, and an explicit risk allowance. It requires a forecast that is updated with current information, not just a number adjusted at period end.
Most importantly, it requires treating the forecast as a management tool rather than a reporting requirement. The point is not to produce an accurate outturn number. The point is to identify, early, what is threatening the margin, and act on it.
See Outturn Forecasting in StoneRise
StoneRise produces live outturn forecasts from real project data for UK main contractors. No spreadsheet builds. No data gathering. A current view of the final account position on every project, any time you need it.
FAQ: Forecasting Project Outturn in Construction
What is project outturn in construction?
Project outturn is the final financial outcome of a construction project: the total cost incurred versus the total value certified, and the resulting margin. Forecast outturn is the commercial team's assessment of where that final position will land, based on current data and projections.
How often should the outturn forecast be updated?
The outturn forecast should be updated as part of every CVR cycle, which for most main contractors means monthly. On projects where margin is under pressure or significant variation activity is taking place, more frequent informal updates are good practice.
What is the most common reason construction outturn forecasts are wrong?
Variation costs that are not fully captured in the forecast final cost. Either because downstream variations have been instructed but not assessed, or because anticipated variations were excluded from the forecast. The cost side of the final account is consistently harder to forecast accurately than the value side.
What is a risk allowance in an outturn forecast?
A risk allowance is a sum set aside in the forecast final cost to cover cost items that are possible but not yet certain: subcontract disputes, potential delay costs, unresolved scope questions. It should be based on a specific risk assessment for the project, not a standard percentage.
Can software improve the accuracy of outturn forecasts?
Yes, significantly. The main source of forecast inaccuracy is incomplete or outdated cost data. Software that connects variation records, subcontract orders, and procurement commitments in real time means the forecast is always based on current data. The judgement element, the risk assessment and the probability weighting, still requires an experienced QS. But the underlying data is more reliable.
