Client concentration is the portion of an accounting practice’s revenue, contribution, or workload attributable to a single client, connected relationship group, or other shared source of economic exposure.
Why does client concentration matter in an acquisition?
It shows how much of the purchase thesis depends on a small number of relationships. Losing one engagement can change debt capacity and staffing economics even when most clients remain.
A practice with hundreds of personal returns may still depend on one employer, referral source, or business-owner family. A CAS firm can have recurring subscriptions but derive much of its contribution from one client group. Revenue recurrence and revenue diversification are separate qualities.
The valuation hub connects concentration with pricing and financing. Do not apply an automatic discount based only on a top-client percentage. First understand the contract, service complexity, relationship holders, collection history, replacement opportunities, and costs that would remain if the client left.
The archived 2014 Journal of Accountancy due-diligence discussion supports investigating client relationships and their history. That process is more informative than accepting a seller’s statement that the large clients have always stayed.
How is the revenue percentage calculated?
Divide the defined client’s eligible revenue by the same-period eligible firm revenue. Use a consistent accounting basis and combine connected entities before drawing conclusions.
Top-client share = client revenue ÷ firm revenue × 100. Top-five share = revenue from the five largest defined relationship groups ÷ firm revenue × 100. Use the same service perimeter in numerator and denominator. If the buyer acquires only tax work, excluded bookkeeping fees cannot dilute the acquired book’s concentration.
Build both legal-client and economic-group views. Several entities with the same owner may make independent operational decisions, but they often share an advisor selection process. Conversely, unrelated clients in one industry need not be treated as one customer; they belong in a separate industry-exposure analysis.
The book of business definition explains the client perimeter. Keep household links, related entities, referral origin, assigned staff, and service categories in a coded roster. The objective is to see economic dependence without disclosing more confidential detail than the review requires.
Why should contribution and workload also be measured?
Revenue alone can miss the practice’s dependence on a profitable client or a specialist-intensive engagement. Show at least an estimated delivery contribution and required hours.
A $90,000 account may generate high contribution if its records are clean and work is standardized. Another at the same fee may require hundreds of owner hours, outside technical review, and slow collection. Losing the first can hurt earnings more; retaining the second may strain capacity. Label allocation assumptions rather than presenting estimated client margins as audited results.
Use directly attributable compensation and vendor costs where possible. Treat shared rent, administration, and quality-control overhead separately. A fully allocated margin answers a different question from short-term profit loss, because shared costs may not disappear when an engagement ends.
Staff concentration can also matter. If one manager knows all major clients and no one else can perform the work, the practice has both client and relationship-holder exposure. Read adjusted EBITDA to translate a specialist departure into replacement cost and sustainable earnings.
What does a downside example show?
It shows the difference between losing revenue and losing profit, then connects that loss to debt obligations. The following inputs are illustrative assumptions for a hypothetical accounting firm.
Assume total annual revenue of $1,400,000 and adjusted operating earnings of $320,000. A connected client group pays $210,000, or 15% of revenue. Direct costs of $72,000 can cease if the group leaves, while assigned payroll and overhead otherwise remain. The model assumes annual acquisition debt payments of $185,000.
| Item | Calculation | Amount |
|---|---|---|
| Client revenue share | $210,000 ÷ $1,400,000 | 15% |
| Short-term earnings loss | $210,000 − $72,000 avoidable costs | $138,000 |
| Remaining earnings | $320,000 − $138,000 | $182,000 |
| Annual assumed debt payments | Model input | $185,000 |
| Pre-other-cash shortfall | $182,000 − $185,000 | −$3,000 |
The 15% revenue loss removes approximately 43% of the original $320,000 earnings under these assumptions. Applying a 15% haircut to earnings would therefore materially understate the short-term effect. The buyer needs a cost-response plan and liquidity, not simply a price adjustment calculated from lost fees.
If only half of the $72,000 costs can cease during the first year, the initial earnings loss is $174,000 and remaining earnings are $146,000. Timely cost reductions matter. Neither scenario is a lender coverage test; the lender’s required deductions and calculation may differ.
How should common-industry and referral exposure be assessed?
Treat shared economic drivers as separate dimensions of concentration. They can create correlated losses even when each client is individually small.
A rural practice serving agricultural businesses may face common weather, commodity, or succession pressures. A manufacturing-heavy firm may depend on a regional employer network. Those patterns do not prove imminent loss, but a buyer should examine whether engagement demand and collections respond to the same shock.
Referral-source dependence is another exposure. A law firm, financial advisor, or local bank might send many clients while having no contractual duty to continue. Determine whether relationships belong to the seller personally, to staff, or to the firm’s service reputation. A transition introduction can help, but do not capitalize future referrals as if they were signed recurring engagements.
Segment the roster by industry, referral source, and service mix without adding the percentages together. A client can belong to several categories; summing them would double count exposure. Show the intersections so the buyer understands the largest combined vulnerabilities.
What evidence supports durability of a large account?
Engagement history, scope, payment behavior, and relationship depth help evaluate durability. A long relationship is evidence to investigate, not a guarantee.
Review engagement letters, renewal patterns, fee negotiations, disputes, unpaid balances, and any notice requirements. Ask who makes the client purchasing decision and whether that person knows more than one professional at the firm. Identify pending client ownership changes, internal accounting hires, or systems projects that may affect future service demand.
The 2014 Journal of Accountancy client-retention discussion connects transition planning with communication and personal relationships. For a concentrated firm, use that guidance to prioritize named responsibilities for key-client introductions and service continuity, subject to appropriate confidentiality controls.
Do not approach clients casually during confidential diligence. Unplanned buyer calls can reveal the transaction before the communication plan is ready. Counsel and the advisor should establish the lawful disclosure and contact sequence. The buyer can often evaluate coded historical evidence before the seller authorizes direct confirmation.
How do sellers and lenders interpret concentration?
Sellers need to demonstrate supported resilience, while lenders need a credible repayment case under stress. Neither audience benefits from hiding connected accounts.
For the seller, document relationship redundancy: who attends meetings, who reviews work, and who can answer client questions when the owner is absent. Retention history for comparable clients and a practical successor introduction plan help explain risk. Diversifying before a sale may take time, so distinguish completed changes from proposed growth.
The SBA 7(a) page describes repayment through business cash flow. A purchaser should therefore ask the lender how large-client loss affects its underwriting, reserves, and financing appetite. This page does not state a universal SBA concentration threshold or assume an approval based on the illustrated percentages.
Read client retention rate for cohort analysis. A ninety-eight-percent count-retention result can coexist with substantial revenue loss when two high-fee clients leave. Lenders and buyers should receive both views with the same underlying roster.
Which steps turn concentration into a decision tool?
Translate the exposure into observable transition actions, downside cash needs, and any negotiated price protections. Measuring the percentage is only the beginning.
- Reconcile client fees to the selected revenue period and transaction perimeter.
- Group connected entities, households, industries, and referral sources separately.
- Estimate contribution and identify costs that cannot fall immediately after loss.
- Review engagement rights, relationship depth, and pending client changes.
- Run loss scenarios with realistic staffing response and cash-reserve timing.
- Assign successor relationship holders and an approved communication sequence.
Price protection may include a targeted retention provision or deferred consideration, but it should not replace a viable operating model. The buyer might need additional working capital even if the price ultimately adjusts. The seller should understand whether one large relationship creates a disproportionate amount of contingent-price exposure.
A few common questions
What else should you know?
What concentration percentage is too high?
There is no universal cutoff that makes every accounting firm acceptable or unacceptable. Assess relationship durability, service margin, connected entities, cost flexibility, and financing. A smaller client can dominate profit while a larger client contributes little. Model the actual loss and cash response before translating concentration into price or terms.
Should related companies be counted as one client?
Show both legal-entity and connected-group views. Separate engagements may share ownership, management, or one advisor-selection decision, so several small invoices can represent one significant economic relationship. Preserve the mapping and explain the grouping criteria. The purchase perimeter and any contractual retention formula should use consistent definitions.
Can a retention clawback eliminate concentration risk?
It can shift some purchase-price exposure, but it does not replace lost operating cash immediately. The buyer may still carry payroll, rent, and debt while an adjustment is calculated or disputed. Test the operating downside separately, and then examine the timing, cap, and conditions of the contractual protection.
Does a diversified tax book have no concentration risk?
It may have little single-client revenue exposure while relying on one preparer, employer network, referral partner, or industry. Those common dependencies can affect many clients simultaneously. Review relationship ownership and operational capacity as well as client shares. Diversification should describe the economic sources of risk, not only the number of returns.
Which sources support this guide?
Primary rules and guidance support the factual statements in this article. The worked examples and decision frameworks are original educational analysis.
- Do’s and don’ts of due diligence — Journal of Accountancy
- How to maximize client retention after a merger — Journal of Accountancy
- 7(a) loans — U.S. Small Business Administration