Work in Progress (WIP) is one of the most consequential figures on a construction company's balance sheet. Get it wrong and your reported profit is wrong. Get it wrong consistently and your financial statements are unreliable, your project decisions are made on bad data, and your auditors have questions you cannot answer cleanly.
Most construction businesses under $10M manage WIP in spreadsheets. It works, more or less. The volume of projects is manageable, the finance team knows every job by name, and the monthly WIP schedule takes a day or two to pull together. It is manual, but it is contained.
Above $10M, that model starts to break. By $30M, it is usually a genuine problem. Here is why.
What WIP accounting actually is
In construction, revenue recognition follows the percentage of completion method. You do not recognise revenue when you invoice. You recognise it as work is performed. WIP represents the value of work completed but not yet billed, or in some cases, amounts billed in excess of work performed (which appears as a liability).
The calculation requires knowing, for each active project: the total contract value, the estimated total cost to complete, the costs incurred to date, and the percentage of completion. From those inputs, you can calculate recognised revenue, gross profit to date, and the WIP balance, which is the difference between what you have earned and what you have billed.
It is not a complex calculation. The problem is doing it accurately, at scale, every month, across dozens of projects, with data that lives in different systems.
Why spreadsheets fail
Data is stale by the time it is compiled. Project cost data lives in your accounting system. Forecast-to-complete estimates live with project managers. Contract variations are approved in emails. By the time your finance team pulls all of this together into a WIP schedule, the data can be two to four weeks old. You are making decisions based on a position that no longer exists.
Manual entry creates errors. Every number that has to be typed from one system into another is a potential error. Cost overruns get missed. Variation amounts are entered incorrectly. A formula row is inadvertently deleted. In a spreadsheet WIP schedule with 40 active projects, errors are not a risk. They are an inevitability.
Reconciliation is a manual process. The WIP schedule should reconcile to the general ledger. On a spreadsheet, that reconciliation is a separate manual step. It is time-consuming, it is often skipped under pressure, and when it does not reconcile, diagnosing the variance takes hours.
There is no audit trail. When an auditor asks why the WIP balance changed by $400,000 between March and April, a spreadsheet cannot tell them. There is no history of who changed what, when, or why. This is a material weakness in internal controls.
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What purpose-built WIP tracking looks like
In Sage Intacct, WIP is a native function. Project costs are captured in real time as they are incurred. Forecast-to-complete estimates are maintained inside the system by project managers. Contract values and approved variations are tracked against each project record.
The WIP calculation runs automatically. There is no month-end schedule to build. The system produces it on demand. Revenue recognition is automated based on percentage of completion. The balance reconciles to the general ledger because it is the general ledger.
For a construction business managing 30 active projects, the difference in finance team time between a spreadsheet WIP process and a system-driven one is typically three to five days per month, every month. Over a year, that is weeks of finance capacity redirected from data entry to actual analysis.
The cost of getting it wrong
Beyond the time cost, inaccurate WIP has direct financial consequences. Understated WIP means understated profit. You may be under-distributing earnings or under-reporting to lenders. Overstated WIP is worse: it inflates the balance sheet and can mask project losses until they crystallise at completion.
For businesses with bonding requirements, bank covenants tied to profitability, or investor reporting obligations, WIP accuracy is not an operational nicety. It is a compliance requirement.
Spreadsheet WIP works until it does not. The inflection point for most construction businesses is somewhere between $10M and $20M in turnover, or when the number of active projects exceeds what one person can manage manually. If your finance team is spending more than a day each month building the WIP schedule, it is worth understanding what a system-driven approach would cost, and save.
See also: how Sage Intacct handles construction accounting and take the free construction finance diagnostic to see where your business stands.