Why Buyers Don't Trust Your ROI Numbers (And How to Fix It)
Research shows buyers discount vendor ROI claims by 50% or more. Here's how transparent inputs, source attribution, and realistic timelines earn trust back.
Here is an uncomfortable truth: your buyer is cutting your ROI numbers in half.
Not because the math is wrong. Not because they think you are lying. But because they have learned, through years of experience with vendor claims, that ROI projections are systematically optimistic. The inputs are generous. The assumptions are aggressive. The timeline assumes instant adoption. And the final number is always conveniently large enough to justify the purchase.
So they discount. It's common knowledge among procurement teams that vendor ROI projections get discounted heavily — sometimes by half or more — before they reach the CFO. Some buying committees have formal policies: "Take any vendor projection and divide by two before presenting to the CFO."
This is not a math problem. It is a trust problem. And solving it requires rethinking how business cases are built, presented, and substantiated.
The Three Trust Gaps
When we talk to buyers about why they discount ROI claims, the same three themes surface repeatedly.
Gap 1: Opaque Inputs
The most common objection is not "your number is wrong." It is "I do not know where your number comes from."
A business case claims $400K in annual savings. The buyer asks: "How did you get that?" The rep opens a spreadsheet and points to a cell. The cell references another cell. That cell uses a hardcoded assumption. Nobody remembers where the assumption came from.
This is the opacity problem. The final number might be reasonable, but the buyer cannot verify it because the inputs are untraceable. Without traceability, trust defaults to zero.
What buyers actually want is simple: show me every number, tell me where it came from, and let me change the ones I disagree with. That is not an unreasonable ask. But most business case tools make it surprisingly hard to deliver.
How Minoa solves this: Every input in a Minoa business case has an input detail drawer that shows three things:
- The current value and how it was derived (manual entry, benchmark, AI estimate, or customer-provided)
- Benchmark context from industry averages and similar customer data, so the buyer can see whether the assumption is conservative, moderate, or aggressive
- History of changes showing how the input has evolved through the deal cycle and who changed it
When a CFO asks "where did this number come from?" the answer is not a vague gesture at a spreadsheet. It is a specific, traceable provenance chain. The input was benchmarked from 23 similar deals in your industry, adjusted by the buyer's VP of Operations based on their internal data, and last updated on Tuesday.
Gap 2: Unknown Authorship
Closely related to opacity is the question of ownership. Buyers discount numbers differently depending on who provided them.
A number provided by the vendor? Heavy discount. A number validated by the buyer's own team? Minimal discount. A number sourced from a credible third-party benchmark? Moderate discount. A number the buyer entered themselves? No discount at all.
Most business cases do not track this distinction. Every number looks the same regardless of whether the vendor made it up, the buyer's CFO confirmed it, or it came from an industry analyst report.
How Minoa solves this: Input ownership tracks the source of every number in the business case:
- Buyer-provided — the customer entered or confirmed this value
- Rep-provided — the sales team entered this value based on their assessment
- Benchmark-derived — this value comes from industry data or similar customer outcomes
- AI-estimated — this value was suggested by Minoa's AI based on available context
Each source type is visible in the business case. When the buyer's team reviews the model, they can immediately see which numbers they own and which numbers need validation.
This changes the dynamic of the business case conversation. Instead of "here is our projection, do you agree?" the conversation becomes "here is the model. You provided these inputs. We benchmarked these. The AI estimated these. Which ones should we refine together?"
That collaborative approach builds trust because the buyer becomes a co-author of the model, not a passive recipient of a vendor claim.
Gap 3: Unrealistic Timelines
The third trust gap is temporal. Most business cases assume full value from day one. The annual projection is divided evenly across twelve months. The buyer looks at the Q1 number and thinks: "There is no way we will see that much value while we are still implementing."
They are right. And that one unrealistic assumption contaminates the entire model. If the timeline is wrong, what else is wrong?
How Minoa solves this: Use case ramping lets you model realistic adoption curves for each use case in the business case. Instead of flat monthly value, you define a ramp: maybe 10% of projected value in the first two months during implementation, 40% by mid-year as the team is trained, and full value by month eight.
Timeline notes explain what happens during each phase, connecting the financial projection to a concrete implementation plan the buyer can validate.
The paradox is that showing less value early makes the total projection more believable. A ramped model signals that you understand the buyer's reality. A linear model signals that you have not thought about it.
Building a Trustworthy Business Case
Trust is not a single feature. It is the cumulative effect of transparency across every element of the business case. Here is a framework for building business cases that buyers actually believe.
Step 1: Make Every Input Traceable
Before presenting any business case, audit the inputs. For each one, you should be able to answer: Where did this number come from? Is it a benchmark, a customer-provided value, or an estimate? When was it last updated?
If you cannot trace an input to its source, the buyer will not trust it. And they should not.
Step 2: Attribute Every Source
Label every input with its provenance. Buyer-provided numbers should be marked as such. Benchmark-derived numbers should reference the benchmark. AI estimates should be transparent about being estimates.
This labeling serves two purposes. First, it helps the buyer understand the model. Second, it creates natural points of collaboration. "These three inputs are benchmarks. Can you validate them against your actual data?" That question transforms the business case from a pitch into a working session.
Step 3: Model Realistic Timelines
Replace linear projections with ramped value curves. Use implementation data from similar customers to set realistic ramp schedules. Add timeline notes that describe what happens during each phase.
When the buyer's project manager reviews the timeline and says "that looks about right," you have earned a level of trust that no dollar figure can achieve on its own.
Step 4: Include Non-Financial Value
Some of the most compelling outcomes resist dollar conversion. A security platform that reduces critical vulnerabilities from 47 to 3 is valuable regardless of the dollar figure attached. An HR tool that saves 6,200 hours per year matters to the VP of Talent Acquisition in hours, not dollars.
Non-monetary calculations let you express value in the units buyers actually use. This avoids the credibility trap of speculative financial conversions and lets each stakeholder see value in their own language.
Step 5: Show the Formula
When a buyer clicks on any number in the business case, they should see exactly how it was calculated. The inputs, the formula, the result. No black boxes.
Minoa's calculation engine provides calculation popovers that render the full formula for any output. Delta charts show how changing a single input affects the result. For custom calculations, the popover displays the actual formula used.
This level of transparency is unusual in business case tools. That is precisely why it works. When everything else in the buyer's evaluation is a black box, the vendor who shows their work stands out.
The Compounding Effect of Trust
Each of these practices builds trust individually. Together, they compound.
A business case with traceable inputs, attributed sources, realistic timelines, non-financial value, and visible formulas is fundamentally different from a spreadsheet with a big number at the bottom. It is not just more credible. It is more useful. The buyer can engage with it, challenge it, refine it, and ultimately defend it to their own stakeholders.
That last point is critical. The buyer is not the final audience for your business case. Their CFO is. Their procurement team is. Their board is. A business case that the buyer trusts is one they will present confidently to internal stakeholders who were never in the room during the sales process.
When the champion walks into the CFO's office and says "I built this model with the vendor. I provided these inputs. The benchmarks come from our industry. The timeline is realistic based on our implementation capacity" — that is a business case that does not get cut in half.
That is how you earn back the 50%.
Frequently asked questions
How should a CFO assess a vendor's ROI claim?
By checking three things before looking at the headline number: where each input came from, who chose the assumptions, and what the timeline assumes about adoption. An input traced to the customer's own data is evidence. An input sourced to an industry average is a hypothesis, and should be labelled as one. The quickest test is to ask the vendor to show the formula. A vendor who can produce it has usually thought about the model; a vendor who cannot is quoting an output they do not control.
What evidence does it take to show a software investment paid off?
A baseline from before the purchase, the same measurement taken afterwards, and an honest account of what else changed in the period. The baseline is the part teams skip and the part that cannot be reconstructed later, which is why it is worth capturing during the evaluation even when nobody is asking for it yet. Without it, the post-purchase number has nothing to be compared against and the conversation falls back to opinion.
Why do buyers discount vendor ROI projections?
Because the projections have been systematically optimistic for long enough that discounting is now a reasonable default. Inputs are generous, assumptions are aggressive, and the timeline usually assumes instant adoption. Some buying committees apply a formal haircut before a vendor number reaches finance. The discount is not an accusation of dishonesty, it is a correction for a pattern, and it applies to accurate projections and inflated ones alike.
Does a conservative projection actually win more deals?
It wins the ones that turn on credibility, which are most of the large ones. A smaller number that survives scrutiny is more useful to a champion than a larger one they have to defend without help, because the champion is the person who has to carry it into a room you are not in. The practical approach is to model a conservative case and an expected case, show both, and let the buyer choose which to approve against.
Should you show the formula, or does that invite argument?
Show it. The argument you are worried about happens either way, but when the formula is hidden it happens without you in the room and the outcome is a flat discount. When the formula is visible, disagreement lands on a specific assumption that can be changed, which turns a rejection into an adjustment. Transparency also transfers some ownership of the number to the buyer, and a number a buyer helped build is one they will defend internally.
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About the Author
Co-founder & CEO at Minoa
Max Elster is the Co-founder and CEO of Minoa. With extensive experience in enterprise sales and value engineering, Max is passionate about helping B2B SaaS companies transform how they sell and communicate value to customers.
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