Revenue leakage: where earned revenue goes missing between your CRM and your ledger

What revenue leakage is, and what it isn't

Revenue leakage is revenue you have earned but never billed or collected correctly. SPI Research, which publishes an annual benchmark for professional services firms, describes it as the gap between earned and realised revenue, often caused by missed billing, scope creep, write-offs or weak contract controls.

It helps to separate it from three things it is often confused with:

• Bad debt is revenue you invoiced correctly but the customer didn't pay.
• Churn is a customer leaving, so future revenue disappears.
• Pricing too low is a commercial choice, even if a poor one.

Leakage is different because nobody chose it. The work was done and the customer expected to pay, but the invoice was missing, short or wrong. That is also why it tends to stay hidden: nobody is chasing a payment that was never requested.

How much are businesses losing?

The honest answer is that it varies widely, and the best evidence comes in several different forms. Here is what we found, and what each source can and can't tell you.

Professional services firms: about 4.5% of revenue. The most useful benchmark for services businesses is SPI Research's 2026 Professional Services Maturity Benchmark, published in February 2026 and based on 509 firms. It found average revenue leakage of 4.5% in 2025, the lowest in five years. Leading firms kept it below 3% through tighter controls and automation. Two cautions apply. The full report is a paid publication, so we have relied on summaries from its sponsors. And the firms in the sample are fairly large (together they account for about $63 billion in services revenue), so a smaller business could land above or below the average.

An industrial manufacturer: 3 to 5% of EBITDA. In its article on order-to-cash optimisation, McKinsey describes one B2B industrial manufacturer that used process mining on its order-to-cash data. It found that broken processes caused leakages at several steps, together equal to 3 to 5 percent of EBITDA. That is one company, measured against profit rather than revenue, so it shows the scale of what can hide in the process and isn't a rate to apply to your own business.

A US wealth manager: 3 to 4% of revenue. Deloitte describes a case in which a large US asset and wealth management firm had 3 to 4 percent of its revenue leaking because contracts and client invoices didn't match. Over ten weeks it found the leakage across 20,000 transactions. It is a single client case study on a consultancy's own website, but it is close to the problem we are describing: what was agreed and what was billed had drifted apart.

Consulting hours: roughly 15% never billed. A study by London Business School and the time-tracking firm TIQ, reported by Consultancy.uk, found that around 15% of chargeable consulting work was never billed to clients. This is about time that isn't recorded, not about invoices that go missing, and it dates from around 2016 and involved a software vendor. It is still a useful reminder that unbilled work is a real feature of services businesses.

A word on bigger numbers. You will see claims online that businesses lose 10%, 20% or even 30% of revenue. Those figures usually come from software vendors or from surveys with very broad definitions, and we haven't been able to trace them to independent research. Treat them with care.

Taken together, the credible evidence points to low single digits as a percentage of revenue, with large differences between firms. For a services business turning over £5 million, a leakage rate of 3% would mean £150,000 a year (an illustrative figure, not a prediction). Because the work has already been delivered, most of that would drop straight into profit if it were recovered.

Why it happens between the CRM and the ledger

In most businesses, the people who sell and the people who bill use different systems. Deals close in a CRM. Invoices are raised, and revenue recorded, in an accounting system. Every step between the two is a place where something can slip.

McKinsey's article on lead-to-cash calls this a classic “elephant problem”. Finance sees a controls issue, sales sees a speed issue and IT sees a complexity issue, and nobody sees the whole. It also notes that most companies have no natural owner for the process, that data often doesn't flow completely between systems, and that a mismatch between what was sold and what was delivered can cause leakage further down the line.

For services businesses, the causes tend to be practical and familiar:

• Amended statements of work. The deal in the CRM changes, but the invoice follows the original figure.
• Retainer overages and extra hours. Approved by email, never billed.
• Milestones that don't trigger an invoice. The work is done and the billing event is forgotten.
• Renewals and upsells. Closed in the CRM, never raised in the ledger.
• Partial invoices. The first part goes out and the balance never does.
• Re-keying errors. A wrong amount or customer name when someone copies details between systems.
• Duplicates and credit notes. They distort what was actually billed.

None of these needs anyone to be careless. They are what happens when two systems that should agree rely on people to keep them in step.

Why the usual checks miss it

Most finance teams do monitor their revenue. The trouble is that the standard measures aren't designed to catch this kind of gap.

McKinsey's order-to-cash article makes the point directly. Typical measures such as days sales outstanding, bad debt and perfect order may not capture leakage at all. In the manufacturer it studied, reported bad debt looked like 0.1 percent of sales. Once credit memos issued by customer services were included, the figure was nearer 0.4 percent. The losses never reached the collections team, so the usual dashboard couldn't see them.

Sampling has the same weakness. PwC's Middle East practice notes that traditional revenue assurance relies on sample-based monitoring, which can overlook hidden issues, especially in businesses with high transaction volumes. If a team spot-checks 15 out of 1,000 closed deals, a missing invoice has a very good chance of passing unnoticed. (Those numbers are illustrative, but the logic holds.)

There is also a gap in the research itself. A 2025 systematic review of revenue leakage, published as a preprint, concluded that the topic is underexplored in academic literature, with much of the available knowledge coming from industry reports. That is one more reason to be careful about which numbers you repeat.

What good looks like

The firms with the lowest leakage don't rely on heroics. Based on what the sources describe, a few habits stand out:

1. A named owner. Someone is accountable for the path from closed deal to correct invoice, so it isn't left between sales and finance.
2. A clear billing trigger for every deal type. A milestone, a date, an approved change. People should know what makes an invoice happen.
3. One place to record scope changes. If an amendment is agreed, it goes on the deal, not only in an email.
4. A regular check of every closed deal against the ledger, not a sample. The more often it runs, the sooner a gap is caught and the easier it is to fix. Late invoices are harder to raise and harder to defend.
5. Humans in the loop. The Deloitte case combined automated matching with a workflow that let staff step in where judgement was needed. Automation finds the gap, and a person decides what to do about it.
6. A record of why gaps happen. Fix the process, not just the invoice, or the same gap will return next month.

SPI's finding that leading firms keep leakage below 3% through tighter controls and automation fits the same pattern.

How to measure your own leakage in an afternoon

You don't need software to get a first estimate. You need a spreadsheet and a few hours.

1. Choose a period. The last 60 to 90 days is enough.
2. Export closed deals from your CRM: deal name, customer, amount, close date and deal ID.
3. Export invoices from your accounting system for the same period plus a margin: invoice number, customer, reference, amount and date.
4. Match them. Start with any shared reference, then customer and amount, then customer and date window.
5. List the exceptions: deals with no invoice, invoices with no deal, and amounts that differ.
6. Sort the real gaps from the noise. Some differences are timing (the deal closed this month and the invoice goes out next month), VAT or currency. Others are genuinely unbilled or part-billed.
7. Work out the rate. Take the value of the genuine gaps, divide it by the value of everything you expected to bill, and multiply by 100.

Treat the result as an estimate. It will be rougher than a continuous check, but it will tell you whether the problem is worth more of your time. Repeat it in a month to see whether the gaps are growing or shrinking.

Where Auditor Alpha fits

Auditor Alpha does the matching described above, automatically and on a schedule. It connects to HubSpot and Xero with read-only access, compares closed deals against invoices, and flags any deal that was never invoiced or only partly invoiced. Each flag comes with the evidence behind it and a suggested fix, and your team reviews every finding and decides what to do. Nothing is written back to your systems.

If you want to see what a check would find in your own data, you can start with a free 7-day Revenue Health Check, which reviews the last 60 days of deals and then keeps checking every two hours. Our first-month Assurance Guarantee covers monthly plans, and terms apply. You can read more about how we think about the benchmarks on our methodology page.

Sources

We have listed these so that you can check them yourself. Where a source has limits, we say so.

1. SPI Research, 2026 Professional Services Maturity Benchmark (opens in a new tab) (19th edition, February 2026). The full report is paid. Summaries by sponsors: Rocketlane (opens in a new tab) and Deltek (opens in a new tab).
2. McKinsey & Company, “Finding hidden value with order-to-cash optimization” (opens in a new tab), 31 May 2022.
3. McKinsey & Company, “Lead-to-cash: the elephant in the room” (opens in a new tab), 13 December 2024.
4. Deloitte, “Stopping revenue leaks with natural language processing” (opens in a new tab), client case study.
5. Consultancy.uk, “15% of chargeable consulting work is not billed to clients” (opens in a new tab), reporting a study by London Business School and TIQ (about 2016).
6. PwC Middle East, “Revenue assurance: a strategic imperative in today's complex business landscape” (opens in a new tab).
7. “Unearthing Hidden Losses: A Systematic Review of Revenue Leakage”, Research Square preprint, March 2025: doi.org/10.21203/rs.3.rs-6229490/v1 (opens in a new tab).

Figures in this article come from the sources above. Worked examples marked as illustrative are for explanation only. Benchmarks and case studies are not guarantees, and your own results will depend on your billing process.