Source: https://www.quantsurv.com/library/construction-cost-at-completion Content format: Markdown version of the public page. Content reviewed: 2026-10-11 # How do I forecast what my project will cost at completion? A cost-at-completion forecast combines the cost already established with the work and risk still ahead. Payments to date tell only part of the story. by [Jack Butler-Kettle]() · About 4 min readShare ## Before you start Gather the budget, contracts and orders, change register, assessments, payments and remaining procurement scope. Include professional costs and tax on the chosen basis. For a client, the central question is the expected total expenditure against the approved budget. That differs from a contractor’s [cost value reconciliation](), which compares cost and value. Use a stated reporting date and one consistent scope. [RICS cost-reporting guidance]() supports clear reporting of cost movements, risk and the forecast position. ## Step-by-step guide 1. ### 1. Set the budget and reporting basis Record the approved budget and what it includes. Fix the reporting date, design issue, currency and tax treatment. Keep an unchanged baseline and a separately approved revised budget where necessary. Show why the two differ. Identify who supplied and checked each contract, order or forecast amount. 2. ### 2. Reconcile each contract and work package Start with the original commitment and add agreed adjustments. Show pending changes separately with an explained forecast assessment. For unplaced work, use the current estimate for the remaining scope. Remove superseded allowances when a contract or quotation replaces them. Choose either full forecast package values or incurred cost plus remaining cost. Mixing both methods without reconciliation double counts expenditure. 3. ### 3. Distinguish the forecast final account A forecast final account predicts the eventual value of one contract. It includes the original sum, expected adjustments and assessed outstanding matters. An agreed final account is a settlement of that contract’s value. A forecast is not an agreement, certificate or payment notice. The whole-project forecast also includes other contracts, fees, owner purchases, applicable tax and remaining project risks. 4. ### 4. Report uncertainty and movements Explain additions, omissions, allowance replacements and changed assumptions since the last report. Identify the documents supporting material movements. Keep [remaining risk allowances]() visible. Do not present disputed or unpriced items as confirmed zero cost. Report the current forecast against the budget and set actions for unresolved decisions. 5. ### 5. Show cash separately and decide the next action Reconcile payments to contracts and assessments. Forecast when the unpaid balance will become payable, including retention and payment terms where applicable. Do not subtract payments from the total project cost to make performance look better. Payments affect the remaining cash requirement. Our [Project cost reporting]() service reconciles commitments, changes and remaining allowances into a forecast final construction cost. **Before you finish:** Reconcile the forecast to the previous report and budget. Separate agreed costs, forecasts, risks and the cash still to pay. ## Worked example ### The facts A fictional project has a £400,000 original building contract. The figures below exclude tax and other separately reported costs. ### What happens 1. Agreed changes are £20,000 and assessed pending changes £10,000. The forecast building account is £430,000. 2. Other project costs are £40,000 and remaining risk £15,000. The total forecast is £485,000. 3. Payments of £250,000 across that same scope leave £235,000 forecast cash to pay. They do not reduce the £485,000 forecast cost. ### What this shows The contract forecast, whole-project forecast and remaining cash answer three different questions. ### Forecast final cost report Remove overlap between actual cost, commitments and remaining estimates. Record the cutoff date and the source of each remaining-cost forecast. [Download blank Excel workbook]() Free blank template for your own project. The completed example is shown below. No email address required. View the completed example Completed fictional example Westhaven refurbishment · 14 October 2026 · Version 1.0 #### Forecast final cost report Scroll across if needed to read the whole record. A dash means no value has been entered. Forecast final cost report: completed fictional example | Package / cutoff | Budget (£) | Cost to date (£) | Unpaid commitments (£) | Uncommitted remaining (£) | Forecast final (£) | Forecast over budget (£) | Basis / action | | --- | --- | --- | --- | --- | --- | --- | --- | | Partitions / 30 Sep | £100,000.00 | £60,000.00 | £25,000.00 | £20,000.00 | £105,000.00 | £5,000.00 | £5,000 forecast overrun; review remaining labour | | Ceilings / 30 Sep | £80,000.00 | £30,000.00 | £40,000.00 | £5,000.00 | £75,000.00 | \-£5,000.00 | £5,000 below budget; scope and accruals checked | Positive variance means forecast over budget. Exclude already-recorded accruals from unpaid commitments to avoid counting them twice. ## Sources 1. [RICS Cost reporting, first edition](). RICS. [Browse the Library]()