There are five common ways owners track how much they depend on their biggest customers. Here's what each one is good at, what it costs, and where it leaves a gap.
Software that shows revenue by customer over time
If you searched for this, you already know the problem. You want to see, without building it by hand, how much each customer contributes and whether any of them is getting too big.
There's no shortage of tools that can show you. The question is which one fits a small business that doesn't have a finance team, and what each one leaves you to do yourself.
Below is a fair look at the five options owners usually land on. None of them is bad. They just solve different problems.
Option 1: The spreadsheet
Export sales by customer, sort it, divide by the total. It's free and it works.
Where it shines: full control, no learning curve, and you can add your own logic, like grouping related companies or separating one-time projects.
Where it falls short: it's a snapshot. Every month you rebuild it, and most owners stop after the second time. It also doesn't warn you; you have to remember to look. Most small business owners already carry the finance work themselves: 41% handle accounting and finance on their own (OnPay, 2019). Adding a monthly manual rebuild is exactly the kind of task that falls off.
Option 2: Your accounting software's built-in reports
QuickBooks, Xero and FreshBooks all have a sales by customer report. In QuickBooks Online it's Sales by Customer Summary, and many versions let you show each customer as a percent of the total.
Where it shines: you already pay for it, and the data is always current.
Where it falls short: it's a table, not an analysis. It won't show trend lines for your top five, won't flag a customer crossing 25%, won't merge duplicate names, and won't run a what-if on losing your biggest account. You get the raw ingredients, not the meal.
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173 systems most businesses rent, what each one replaces, and what it costs a typical 10-person company every month. Tick what you pay for, circle three, and see what owning them would look like.
Download the free Blueprint →Option 3: Fathom and Reach Reporting
These are management reporting tools that connect to your accounting system and turn it into dashboards and polished reports. Searches like "fathom customer concentration report" are common because these tools can show revenue by customer and track KPIs over time.
Where they shine: good-looking reports, multi-period comparisons, and they're built for accountants and advisors who manage many client files. If your CPA or fractional CFO already uses one, ask for a concentration page in your monthly pack.
Where they fall short for a small business: they're another login and another subscription, and they're designed around a broad set of reports rather than one specific alert. Our Blueprint estimate for this category is about $65 a month for a typical 10-person company, or $3,900 over five years. And when you cancel, the reports you built go with it.
Option 4: BI tools like Power BI or Looker Studio
Business intelligence tools can do almost anything with your data if someone sets them up. Looker Studio is free to use; Power BI has free and paid tiers.
Where they shine: unlimited flexibility and great charts.
Where they fall short: setup. Connecting accounting data, cleaning it, and building the measures takes real skill. Many small businesses start these projects and never finish. It's a common pattern: roughly 60% of SMBs made a software purchase they regretted in the past 18 months (Capterra, 2024).
Option 5: A fractional CFO or consultant
Searches like "fractional cfo customer concentration risk" and "do I need a consultant to tell me I rely on one client too much" are real questions owners ask.
Where it shines: judgment. A good CFO doesn't just show the number; they help you price the risk, renegotiate terms, plan the pipeline and prepare for a sale.
Where it falls short: it's the most expensive option, and you're paying senior rates for something a system could calculate. The best use of a CFO is the conversation about what to do, not the hours spent producing the table.
What all five have in common
Every option above either needs you to remember to look, or charges you monthly to look for you. None of them, out of the box, does the one thing that matters most: tells you, unprompted, when a customer is getting too big.
That gap matters because most owners aren't watching. 70% of SMB owners said they lack daily insight into company performance, and only 1 in 10 tracked growth targets in real time (Geckoboard, 2016). The ones who did track in real time were twice as likely to hit all their goals.
Meanwhile software costs keep climbing. Average SaaS spend reached $4,830 per employee, up 21.9% in a year (Zylo, 2025). Another dashboard subscription is the default answer, but it isn't the only one.
What owning the system looks like instead
The alternative is a small system built with your own AI, inside your own accounts, that does the job end to end:
- Pulls sales by customer from your accounting system on the first of every month.
- Applies your cleanup rules: merges duplicate names, groups related companies, tags one-time projects.
- Calculates trailing-12-month share for your top 1, 5 and 10, plus the trend.
- Runs the "what if our biggest customer left" math against your fixed costs.
- Sends a plain-English summary to your email or Slack, with an alert first if anyone crossed your limit.
You keep it forever, including if you stop working with whoever built it. You pay your own AI usage, which for a monthly report is small. And it replaces the subscription you'd otherwise pay for separately, rather than adding one.
Which option fits you
If you want a one-time answer, use the spreadsheet tonight. If your accountant already runs Fathom or Reach Reporting for you, ask them to add a concentration page. If you need strategy, hire the CFO for the decisions, not the data.
A quick test before you buy anything: write down the three questions you want answered every month. If a tool answers all three without you exporting anything, it's a fit. If you'd still be exporting, sorting and dividing, you're paying for a dashboard and doing the work yourself.
If you want the number in front of you every month without paying rent for it, own the system. The point isn't the tool. It's never being surprised by your own customer list again.
Questions owners ask
Does Fathom have a customer concentration report?
Fathom and similar tools can show revenue by customer and track it over time from your accounting data. Whether you get a ready-made concentration page depends on how your reports are set up; your accountant can usually add one.
Can I just ask my bookkeeper to send this every month?
Yes, and many will. Agree on the exact format: trailing-12-month share for your top 10, the trend, and a flag for anyone over your limit. The risk is that it slips when they're busy at month-end or tax season.
What's the cheapest way to track customer concentration?
A spreadsheet built from your accounting system's sales by customer report. It's free, but you have to rebuild it every month and remember to look.
Is an owned system better than a reporting subscription?
It depends on what you need. If you want many reports and an accountant manages them, a subscription can make sense. If you want one specific monthly view and alert that you keep, owning it avoids paying rent indefinitely.
Own the system instead of renting it
Valuexus builds it inside your own accounts, usually within 24 hours, and it stays yours even if you cancel. $450 a month, locked for life; your first month is $225 with code WELCOME50. 7-day, 75% money-back guarantee.
See how Valuexus works →Keep reading
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- Profitable but No Money in the Bank? Here's Where the Cash Went
- One Client Is 50% of Your Revenue? Here's What That Really Means
Sources
- 41% of small business owners and managers do accounting and finance themselves; 56% of owners with fewer than six employees do everything themselves — OnPay Small Business Finance and HR Report, 2019
- Roughly 60% of SMBs made a software purchase they regretted in the past 18 months — Capterra Tech Trends Survey, 2024
- 70% of SMB owners said they lack daily insight into company performance; only 1 in 10 tracks growth targets in real time — Geckoboard SMB Growth and Metrics Survey, 2016
- SMBs tracking metrics in real time were twice as likely to hit all growth goals (50% vs 24%) — Geckoboard SMB Growth and Metrics Survey, 2016
- Average SaaS spend reached $4,830 per employee, up 21.9% year over year — Zylo SaaS Management Index, 2025
Written by Hunter J. Schneider, founder of Valuexus. Get your free 173-point AI audit.