A buyer should not treat the seller’s current client list as proof that the same clients and fees will remain after an accounting practice acquisition. Retention has to be tested as a sequence: the client was active before the sale, can lawfully be contacted, accepts the transition, appoints or engages the buyer where required, receives the next service, is billed and ultimately pays.

Investigate that sequence using historical client cohorts, de-identified records, current engagement terms, contact and consent evidence, relationship ownership, service continuity and a documented handover plan. Model downside cases separately from the headline retention assumption; a client who has not objected is not necessarily a retained client.

Retention is a sequence, not one percentage

A seller may describe retention as the percentage of clients who did not formally leave. That measure can overstate what transferred. Build a client-level bridge with clear stages:

Stage Evidence to verify Common gap
Active before sale Recent completed work, invoice and collection Dormant names remain on the database
Eligible for transition Correct entity group, services, contact and consent status Buyer sees personal information too early
Transition accepted Client response, new or updated engagement, required authority Silence is counted as acceptance
First cycle delivered Job opened, records received, work completed on time Client stays listed but sends no work
Fee retained Like-for-like scope billed and collected Price rises or one-offs conceal lost scope

Measure both client-count retention and fee retention. Show opening fees, losses, scope reductions, price changes, scope expansions and new clients separately. Keep gross retention—what remained from the opening cohort—apart from net movement after additions. Segment by fee band, service line, tenure, relationship partner, industry, office, entity type and billing model. There is no universal percentage that proves a practice is transferable; the causes and concentration of departures matter.

Evidence to request before relying on the forecast

Ask for de-identified, stable client identifiers across enough complete service cycles to reveal departures and reactivations. The pack should include:

  • client-group structure, service mix, tenure and fee history;
  • engagement dates, termination provisions and evidence of client acceptance;
  • invoices, credits, write-offs, collections and lost-scope notes;
  • last meaningful contact, preferred channel and contact-data quality;
  • relationship owner, delivery team and seller involvement;
  • complaints, service failures, missed deadlines and unresolved matters;
  • clients won through personal, staff, referrer or related-party relationships;
  • historic departures, stated reasons and the staff member handling each exit; and
  • the proposed communication, consent, authority and re-engagement workflow.

Reconcile cohort fee totals to billing records, the general ledger and bank receipts. Australian Government buyer guidance recommends examining the business’s financial records, operations and legal documents and independently checking three to five years of financial information (business.gov.au). Use that range as a starting point, then adapt it to the practice’s service cycles and data quality.

Privacy limits how this work is performed. The OAIC says a vendor should generally avoid giving a prospective purchaser customer names or other identifiers and should consider de-identification, consent and controlled access (OAIC). Agree the diligence protocol with legal advisers instead of solving a data gap by copying identifiable client files.

Test whether clients can actually transition

Check the legal entity providing services before and after completion. An asset sale to a new practice entity may require a different process from an ownership change within the same entity. Do not assume engagement letters, portal access, direct debits, software permissions or ATO authorisations simply follow the purchase contract.

APES 305 requires members in public practice to document and communicate engagement terms and includes guidance on recurring engagements (APESB). For each material cohort, establish whether the engagement identifies the client entities, services, responsibilities, fee basis and acceptance. Ask what the buyer will issue, what the client must approve and what happens if approval is late.

The TPB’s current transfer guidance says client information must not be disclosed to the buying practitioner without the client’s consent or a legal duty, and expects relevant proof-of-identity records to transfer with other client records when a tax or BAS practice or client list changes ownership (TPB). This makes consent and record-transfer readiness part of operational retention, not merely an administrative task.

For ATO client-to-agent linking, entities with an ABN other than sole traders must nominate a new registered agent when engaging one. The client—not the agent—completes the nomination, and the agent generally has 28 days to add the client before it expires (ATO). Identify affected entities, responsible client contacts and likely support needs before setting the transition timetable.

Investigate why clients stayed or left

Interview the seller and continuing staff separately, then compare their explanations with file notes and cohort movements. Useful questions include:

  • Which clients deal only with the selling partner, and which regularly work with the broader team?
  • Were departures driven by retirement, sale of the client’s business, service quality, price, technology, location or a competing adviser?
  • Which clients have queried the sale, requested fee certainty or delayed records recently?
  • Are key clients connected to one family, referrer, employee or industry network?
  • Will the buyer change brand, location, staff contacts, software, turnaround times or pricing at once?
  • Who will make each introduction, answer objections and record acceptance?

CPA Australia’s practice-sale checklist treats seller availability, client introductions and buyer familiarity with procedures as important handover matters (CPA Australia). Turn general promises such as “the seller will help” into a client-tiered plan with named owners, timing, communication methods and escalation steps.

Build a downside retention case

Use a cohort model rather than reducing every client by the same percentage. Apply greater stress where the relationship is seller-led, engagement evidence is weak, contact details are poor, a material fee rise is planned, service problems are unresolved or the buyer’s delivery model changes sharply.

Hypothetical example: a practice reports $1 million of annual fees. The buyer’s bridge identifies $90,000 from dormant or one-off work, $160,000 from clients solely managed by the departing seller and $120,000 from entity groups that must complete agent nomination. These categories overlap, so they must not simply be added. Instead, the buyer tags each client once, assigns evidence-based scenarios and tests the timing of retained cash and replacement workload. The example is a method, not a benchmark.

Compare the result with staffing capacity and the proposed price terms. Transaction lawyers, accountants and valuation advisers should assess whether any retention adjustment, deferred consideration, warranty or completion mechanism is appropriate; the model alone does not determine the contract.

Frequently asked questions

When is a client “retained”?

Define it before signing. A stronger definition usually requires an accepted engagement or authority, delivery of agreed work and collected fees over a stated measurement period—not merely a name remaining in the system.

Can the buyer contact clients during due diligence?

Only through a process agreed with the seller and legal advisers that addresses confidentiality, privacy, consent and transaction risk. Early diligence can usually begin with aggregated or de-identified information.

Should the seller guarantee retention?

No seller can make a client stay. Advisers can help the parties document transition obligations and any price mechanism, but the buyer still needs an operational plan and a downside case.

Sources

Disclaimer

This article provides general information only. It does not constitute legal, tax, accounting, financial, credit, valuation or other professional advice. Circumstances differ. Obtain advice from appropriately qualified advisers before acting or entering a transaction.