In EleVia's customer case study of Halff, the firm's work-in-progress (WIP) days fell from 27 to 22. Over the same period, annual revenue grew from $97.5 million to $134.8 million, and the unbilled balance rose from $7.2 million to $8.0 million. Halff has an MEP engineering practice, though the published results describe the whole firm, not its MEP practice alone.
MEP principals can ask how much work their team has earned but not invoiced, then compare that balance with revenue to calculate WIP days.
Before: Paper Invoices Across 15 Offices
Halff handled more than 1,000 invoices a month across 15 offices. Its staff printed invoices, marked them up, scanned them, and emailed each one separately. Client-specific invoice requirements lived in binders, and project accountants had limited visibility into where an invoice stood. Joseph Sagel, Halff's financial director, described the process in the EleVia case study.
That workflow made it hard for a principal to see which invoices were ready, which needed a decision, and who owned the next step.
What Halff Changed
Halff implemented Deltek Vision and EleVia's electronic invoicing software. The new workflow put invoice stages in one place, sent billers reminders about outstanding work, and let the team configure review steps for each client's requirements. Sagel said the team became “a lot more efficient and a lot more consistent on a per project basis” in the published account.
With the new system, staff could see each invoice's status and who needed to act next. The published case does not separate the effects of the software from changes to Halff's process.
The Result: Five Fewer WIP Days
The case study reports WIP days falling from 27 to 22, a reduction of five days or about 19%. Sagel estimated a 15–20% improvement in invoicing efficiency. The case study gives no period for reaching those results and makes no claim about cash collected.
Halff's WIP grew from $7.2 million to $8.0 million while revenue grew faster. Using the published figures, WIP divided by annual revenue and multiplied by 365 gives roughly 27 days before and 22 days after. Halff still had $8.0 million of unbilled work to manage, even as its WIP days fell by five.
What an MEP Firm Can Apply
For MEP firms, Halff's case and BaseBuilders' WIP management guidance suggest three billing checks:
- Measure both WIP dollars and WIP days. Pull earned but unbilled work by project and phase. Compare the balance with revenue for the same period to see how much unbilled work the firm carries relative to its size.
- Give every delayed invoice an owner. In the billing review, record why a balance has not reached an invoice, who can clear it, and the next decision date. Halff's previous paper workflow made status difficult to track; its new system gave staff a shared view of invoice stages.
- Check the contract before automating the route. Fixed-fee phases, additional services, and client-specific invoice rules can change when work becomes billable. Project managers need to confirm completed deliverables and billing terms. Software can then route an eligible invoice through the right review steps.
An MEP practice may also have design revisions and scope changes that need an additional-service decision. BaseBuilders describes how unrecorded scope changes can distort a WIP report. The team can raise those items with a principal during a weekly review, while the work and client conversation are still current.
Where AI Fits
Halff's published case concerns electronic invoicing and does not report using AI. For an MEP firm considering AI now, it could flag older WIP balances and assemble supporting notes for a project manager to review. The manager would still check the contract terms and invoice amount before billing.
If your firm wants to map that process before choosing tools, you can book an AI strategy call. We can look at where invoice preparation slows down and which parts of the review your team should keep in human hands.
By Dan Cumberland | Dan Cumberland Labs
FAQ
Did Halff's MEP practice reduce WIP days from 27 to 22?
The published case study reports a firmwide result. Halff offers MEP engineering, but the source does not provide a separate MEP result.
Does a drop in WIP days show how much cash a firm collected?
The case study reports WIP days, WIP balances, and annual revenue before and after the invoicing changes. It does not report cash collections. WIP days measure unbilled work relative to revenue; payment comes after an invoice goes out.
How should an MEP firm measure WIP days?
Start with earned work that has not been invoiced, then divide that balance by annual revenue and multiply by 365. Using the figures EleVia published for Halff, the calculation gives about 27 days before and 22 after. Your accounting team should confirm the revenue measure and reporting period before comparing your firm with another.
