Private Equity
Sales due diligence: what to test in a target's sales engine before you invest
8 mins read
KEY TAKEAWAYS
Sales due diligence tests how the target's revenue is produced: the pipeline, conversion, forecast record, customer retention and sales capacity behind the business plan.
It sits between financial and commercial due diligence. Financial diligence checks the numbers, and market work checks the opportunity. Sales diligence checks whether the engine can deliver the plan.
Ask for the evidence behind each management claim, not the headline. Pipeline history, stage conversion, forecast against actual and how retention is calculated tell you more than any summary slide.
Access is limited before signing. Agree early what must be tested pre-deal and what becomes a first-100-days check, so nothing falls between the two.
With leverage and multiple expansion doing less of the work, more of the return depends on revenue growth. That makes the sales engine part of the investment case.
Sales due diligence tests whether a target's sales engine can deliver the revenue in its business plan. It looks at how revenue is actually produced: how the pipeline converts, how accurate past forecasts were, how well customers are retained and grown, and whether the sales team has the capacity for the growth the plan assumes. Financial diligence tells you what the numbers were. Sales due diligence tells you whether the machine that produced them can produce the next ones.
This guide is for deal partners and operating partners in UK and European mid-market buyouts of B2B companies. It covers what sales due diligence adds, the evidence to request, the management claims to test, red flags, and how findings carry into the first 100 days.
Why the sales engine is now part of the investment case
The arithmetic of returns has changed. McKinsey's 2026 private markets report cites analysis by StepStone Group finding that leverage and multiple expansion made up 59% of returns on deals done between 2010 and 2022. It says operational value creation is now likely to be the primary source of returns, and that underwriting it during diligence "is rapidly becoming table stakes".
Bain's 2026 private equity report describes the same shift. Borrowing costs are now in the 8% to 9% range. Bain estimates a typical deal now needs roughly 10% to 12% annual EBITDA growth to produce the return that cheaper debt and rising multiples once delivered.
In many B2B targets, much of that growth depends on the sales engine, so it's worth testing before signing whether the engine can carry the plan.
How sales due diligence differs from financial and commercial diligence
Each workstream answers a different question, and the sales question can fall between them.
Financial due diligence looks at trading trends, the underlying quality of earnings and, for private equity buyers, "historical budgeting accuracy", according to ICAEW's Guideline 71. It is explicitly not an audit.
Commercial due diligence is defined by ICAEW's Guideline 72 as "an objective enquiry to critique and challenge commercial matters relating to a target entity, including its business plan and financial projections". Its scope can include customer concentration and churn, and pipeline analysis based on CRM data.
Sales due diligence goes deeper on how revenue is produced. That means how deals are qualified and progressed, why forecasts were missed, which segments win, and whether the team can scale.
Scope varies between providers, and commercial due diligence can cover parts of this. Ask expressly whether pipeline conversion, forecast accuracy and sales capacity are in scope, and check that the scope letter names them.
Merlin5's private equity work frames commercial diligence around six questions that financial diligence doesn't answer:
Commercial maturity: how effectively the commercial engine operates today.
Revenue quality: how sustainable current revenue performance really is.
Growth constraints: the factors most likely to limit future growth.
Commercial scalability: the organisation's ability to support the next phase of expansion.
Value creation opportunity: where the greatest commercial gains can be achieved.
Commercial risk: the operational weaknesses that could affect future returns.
Evidence to request
Request data at the level of individual deals and customers, not summaries. ICAEW notes that pipeline analysis needs high-quality pipeline information, typically from a CRM, and may need detailed conversations with management.
Pipeline and conversion
Opportunity-level CRM exports for at least the last eight quarters, including stage history, amounts and close dates.
Win and loss by segment, product, region and deal size.
Average time in each stage, and how close dates moved.
Forecast record
Each quarter's forecast against actual revenue, by quarter and by forecast category.
How the forecast is built, and who can override it.
Customers and retention
Revenue by customer for the last three years, so you can see concentration, growth and loss.
How net revenue retention is calculated, with the customer-level data behind it. PowerSchool's 2022 annual report states that the measure "does not have any standardized meaning", so a headline percentage alone doesn't tell you much.
Sales capacity and cost
Headcount by role, quota, attainment and tenure.
Time for new sellers to reach full productivity.
Discount and pricing approvals by quarter.
The order of these depends on the deal. If you can only get one dataset early, ask for the opportunity-level pipeline export. It lets you test more of the claims in the table below than any other single file.
Management claims to test
Claim in the plan | How to test it | What confirms or challenges it |
|---|---|---|
"The pipeline covers next year's growth" | Rebuild the pipeline by stage, then apply historical stage conversion | The plan holds only if historical conversion, not stated probability, produces the number |
"Win rates are improving" | Compare win rates on comparable deals over eight quarters | Improvement driven by one segment, or by closing out old deals, is weaker than it looks |
"Customers stay and grow" | Rebuild retention from customer-level revenue | Retention that rests on a few large accounts is a concentration risk |
"We forecast accurately" | Compare forecast with actual for every quarter available | Repeated late-quarter changes point to judgement-based forecasting |
"New hires will add capacity" | Check ramp time and attainment of recent hires | Slow ramp or high early attrition delays the plan's growth |
"Pricing is holding" | Review discounting by quarter end and deal size | Discounts that cluster at quarter end suggest pressure to hit targets |
A 2020 Gartner survey links that last pattern to forecasting pressure. It notes that leaders may approve a discount they'd normally reject when they need the revenue to hit the quarter.
Red flags
The CRM and the finance numbers disagree on revenue by customer or period, and nobody can reconcile them.
Stages have no exit criteria, so the pipeline value depends on seller judgement. Our guide to identifying revenue growth constraints covers how to read these symptoms after a deal.
Close dates move repeatedly, and old deals stay in the pipeline. See our guide to stalled deals for the signals.
A few sellers or a few customers carry most of the revenue.
The plan assumes higher win rates or larger deals than history supports, without a stated reason for the change.
Management can't explain why the forecast missed in the quarters it did.
On its own, none of these is a reason to walk away. Each is a reason to revisit the price, the plan or the first 100 days.
What you can test before signing, and what waits
Access is often limited. ICAEW notes that buyers in auction processes are generally prohibited from contacting customers for primary research. Data rooms often hold summaries rather than opportunity-level exports.
Agree a split early:
Before signing: the questions that would change the price or the decision, tested on whatever data is available.
After signing: the questions the 100-day plan depends on.
ICAEW's commercial guideline makes the link directly. Commercial diligence can shape post-deal strategy and 100-day planning.
The same evidence then becomes the post-deal baseline. Merlin5's view, set out on its private equity page, is that diligence evidence can feed directly into the Growth Assessor™, which creates a quantified view of what should change after investment. It starts from the four drivers in our sales velocity formula guide: opportunities, deal value, win rate and cycle length. That makes the baseline comparable before and after the deal.
Post-investment work at Bowmark-backed Littlefish shows the after-signing half of this. A new CRO wanted to know whether the commercial operating model could support the business's ambition to double in size within three years, before committing to change.
When to commission outside help, and what to ask
Bring in outside help when:
the plan depends on a step change in sales performance;
the target's CRM is new, inconsistent or barely used;
the deal team lacks operators who have run a sales organisation of this kind.
You may not need it when the target has a long, clean CRM history, a forecast record that reconciles to finance, and a plan that extends past performance rather than changing it.
Questions to ask a provider:
Who will do the work? Look for people who have run sales teams and carried a number, not only analysts.
Will they work from opportunity-level data, or only from management's summaries?
How will findings be split between pre-signing questions and the 100-day plan?
Will the output rank issues by their effect on the plan, or simply list them?
The five dimensions of commercial maturity on Merlin5's private equity page give a useful structure for that output. The partners behind this work have held CEO, CRO and sales leadership roles in private equity-backed businesses.
Where to start
Ask for the opportunity-level pipeline export with stage history before anything else.
Rebuild one quarter's forecast against actual, and ask management to explain the gap.
List the plan's three biggest revenue assumptions, and decide which must be tested before signing.
Frequently asked questions
Is sales due diligence the same as commercial due diligence?
Not quite. Commercial due diligence tests the market, competition, customers and business plan, and may include pipeline analysis. Sales due diligence goes further into how revenue is produced: conversion, forecasting, capacity and pricing behaviour.
Who should run sales due diligence?
People who have run sales organisations, supported by analysts. Reading a pipeline export well depends on knowing how sellers and managers use the CRM in practice.
What if the target has poor CRM data?
That is itself a finding. Rebuild what you can from finance and contract data. Then treat the CRM gap as a 100-day priority and a risk to the forecast you're buying.
How does it connect to value creation?
The findings become the baseline for the value creation plan. The constraints you find before signing are usually the first things to fix after it. Our guide to value creation levers covers how they compare.
Sources
ICAEW Corporate Finance Faculty, "Commercial Due Diligence", Best-Practice Guideline 72, 2025. https://www.icaew.com/technical/corporate-finance/guidelines/commercial-due-diligence-guideline-72
ICAEW Corporate Finance Faculty, "Financial Due Diligence", Best-Practice Guideline 71, 2024. https://www.icaew.com/technical/corporate-finance/corporate-finance-faculty/guidelines/financial-due-diligence-guideline
McKinsey & Company, "Private equity: Clearer view, tougher terrain", Global Private Markets Report 2026, 10 February 2026. https://www.mckinsey.com/industries/private-capital/our-insights/global-private-markets-report/private-equity
Bain & Company, "Welcome to a New Era in Private Equity", Global Private Equity Report 2026, 22 February 2026. https://www.bain.com/insights/welcome-to-a-new-era-global-private-equity-report-2026/
Gartner, "Gartner Says Less Than 50% of Sales Leaders and Sellers Have High Confidence in Forecasting Accuracy", press release, 12 February 2020. https://www.gartner.com/en/newsroom/press-releases/2020-02-12-gartner-says-less-than-50--of-sales-leaders-and-selle
PowerSchool Holdings, Inc., Form 10-K for the fiscal year ended 31 December 2022, US Securities and Exchange Commission. https://www.sec.gov/Archives/edgar/data/1835681/000183568123000012/pwsc-20221231.htm
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WRITTEN BY
Chris Thomas