Client accounting services, or CAS, is an outsourced accounting service model that can combine transaction processing, closing, reporting, controller support, and advisory work within defined client engagements.
What work belongs in CAS?
CAS should describe the firm’s actual service scope, not imply that every package contains the same services. Different practices use the abbreviation for different combinations of accounting and advisory work.
The CPA.com client advisory services resources presents CAS as a practice area with accounting and advisory capabilities. A transaction reviewer should translate that label into engagement-level tasks: bookkeeping, reconciliations, monthly close, reporting, payroll coordination, controller services, forecasting, or CFO advice. Tax returns and attest reports need separate identification when included elsewhere in the practice.
A business buying a basic monthly close may not have agreed to strategic finance advice. A seller providing informal owner consultations may not charge separately for that work. Confirm which activities are included, which are add-ons, and which depend on the departing owner. A broad service name can conceal both uncompensated scope and specialist staffing requirements.
The valuation hub connects this service model with purchase economics. CAS can support regular fees, but the buyer must inspect the scope, costs, renewal terms, and client operating systems behind those fees.
How does the delivery model differ from annual tax work?
It requires repeated operational coverage throughout the year, often tied to client reporting deadlines. The buyer needs immediate continuity rather than waiting for one annual filing cycle.
Monthly work can depend on bank feeds, client approvals, software integrations, exception resolution, and manager review. A delay in one task can postpone the close and reduce confidence in the client’s reports. Map the workflow from source transactions to final deliverables and identify the person responsible for each handoff.
Client responsibilities matter. An agreement might require timely documents, coding explanations, payroll approvals, or management review. If the client routinely misses those obligations, staff may spend additional time chasing inputs. A fee that looks predictable on a subscription report can therefore require unpredictable effort.
Document service-level commitments and escalation procedures. The successor should know what must happen weekly, monthly, quarterly, and annually. A production plan based only on billable hours misses calendar coverage, client support, and review bottlenecks that can determine whether the service remains usable after the sale.
What makes a CAS engagement transferable?
Clear scope, documented workflows, shared client knowledge, and accessible systems support transferability. Owner-dependent judgment and undocumented exceptions make the handoff harder.
Review which staff can complete recurring tasks without the owner. Determine who understands client-specific account mappings, unusual entries, reporting formats, and business decisions. If only one senior person can explain the work, the purchaser needs a knowledge-transfer plan and a realistic replacement budget.
Software access should be tied to authorized user accounts rather than personal passwords. Identify whether the client or firm owns each subscription and whether licenses or administrator roles can change. Check integration dependencies and export formats before assuming the buyer’s preferred system can immediately replace the existing workflow.
Read book of business for the engagement perimeter and engagement letter for the written service boundaries. A CAS sale must transfer the ability to perform defined work, not simply a list of automatic payments.
How should revenue quality be measured?
Measure fees, retention, scope, workload, and collection together. A monthly recurring revenue total is a starting dashboard rather than a complete valuation.
Reconcile subscriptions to actual invoices and receipts. Separate onboarding fees, catch-up work, annual tax fees, and optional advisory projects from the monthly package. Verify start dates and cancellations; a newly signed client may not yet have experienced a full reporting cycle. Show credits and service pauses rather than treating every invoice as recurring without qualification.
The 2024 CPA.com CAS benchmark announcement reports results from 206 self-selected practices using 2023 data. Its findings describe that respondent group; they do not establish a growth guarantee, acquisition multiple, or margin target for an individual Midwest firm.
Compare mature cohorts with recently onboarded clients. Track service additions, price changes, and departures separately. The recurring revenue definition explains why periodic billing and continuing service need separate evidence.
What does a delivery-economics example show?
It shows how a subscription book can have attractive revenue while requiring substantial recurring labor. The following figures are illustrative assumptions, not actual CAS performance or pricing recommendations.
Assume 48 clients each pay $1,250 per month for a defined accounting package. Annual subscription revenue is 48 × $1,250 × 12 = $720,000. The assumed delivery budget includes staff production, review, client-system costs, and support coverage, followed by shared overhead.
| Component | Annual assumption | Remaining amount |
|---|---|---|
| Subscription revenue | $720,000 | $720,000 |
| Production staff compensation and burden | −$285,000 | $435,000 |
| Manager and technical review | −$115,000 | $320,000 |
| Client-system and integration costs | −$54,000 | $266,000 |
| Client support coverage | −$38,000 | $228,000 |
| Shared overhead | −$92,000 | $136,000 |
The remaining $136,000 is a simplified operating result before financing, taxes, and separately identified investment needs. It assumes all required owner work is covered in the budget. If the owner performs unbudgeted CFO advice worth an assumed $60,000 annual replacement cost, the estimate falls to $76,000.
Losing four clients removes $60,000 of annual subscription fees. If staff and software costs remain unchanged initially, the original $136,000 falls to $76,000 before any additional effects. The monthly billing model does not automatically make costs flexible. The buyer needs capacity and cash planning under both full retention and reduced activity.
How should scope expansion and pricing be evaluated?
Inspect what clients actually receive, not only the package description. Unpaid work can erode the margins supporting the purchase price.
A client may add locations, employees, transactions, or reporting requests while paying the same fee. Determine whether the agreement has volume thresholds, change-order provisions, or annual scope reviews. Review whether those provisions have been enforced; a contractual right to reprice is different from an accepted fee increase.
The 2023 AICPA MAP survey release distinguishes net client fees and expenses from partner compensation when discussing owner profit. That distinction reinforces the need to identify production and owner advisory work separately in a CAS earnings model. Survey results are not the seller’s financial evidence.
Review onboarding economics too. A profitable mature engagement can require costly cleanup and systems setup at the start. If the firm charges onboarding fees, show the related labor and timing. Growth projections that count new subscriptions but omit onboarding capacity can overstate near-term cash generation.
What privacy and professional boundaries require review?
CAS access can include sensitive financial information and authority over client workflows. Determine permissions, data responsibilities, and any independence implications before changing ownership or service delivery.
Identify bank-access levels, payment approvals, payroll roles, and administrator permissions. Separate preparing information from approving client transactions. The buyer should know who has authority to move funds and who reviews the activity. A transaction should not leave departed staff with unnecessary access to the client environment.
If the practice also performs attest work, evaluate nonattest-service responsibilities under the applicable professional standards. Providing useful accounting support does not automatically preserve independence for every report engagement. Use qualified professional review for service combinations, entity structures, and state licensing requirements.
Client communications should explain the successor team and any proposed workflow changes. Avoid promising unchanged service if the buyer intends an immediate platform conversion. A staged migration can require additional support hours; include those costs in transition planning rather than hiding them in expected efficiency savings.
How do buyers, sellers, and lenders use the CAS analysis?
Buyers need a viable year-round service plan, sellers need evidence of recurring fees and manageable scope, and lenders need dependable cash after delivery costs. The engagement economics should be reproducible.
- Separate subscriptions, onboarding, tax, projects, and advisory fees in the revenue schedule.
- Map each package to actual tasks, client duties, and service deadlines.
- Reconcile recurring invoices with collected receipts and cancellations.
- Budget production, review, support, owner replacement, and software access.
- Test lower client activity and additional onboarding under the monthly cash forecast.
Sellers should provide workflow samples and fee histories supporting the operating model. Buyers should verify the required people and systems. Lenders should receive seasonality, collection, and reserve assumptions alongside the earnings bridge.
A few common questions
What else should you know?
Is CAS just another name for bookkeeping?
Some packages mainly provide bookkeeping, while others add close management, reporting, controller support, or strategic advice. The acronym does not establish a uniform service promise. Review each engagement’s written scope and actual delivery tasks. In a sale, those differences change staffing, fees, transition needs, and the buyer’s operating capacity.
Do monthly CAS subscriptions guarantee client retention?
No. Clients may have cancellation rights, reduce scope, or leave if reporting and support deteriorate. Reconcile signed engagements with actual renewals, invoices, and receipts. A subscription model supports predictable billing only when the service relationship continues and the firm has enough qualified people and systems to deliver it.
How should a seller’s informal CFO work be valued?
Identify the duties, time, required expertise, and whether the client pays for them. If the work continues after closing, include a supported replacement cost or the buyer’s compensated role. Informal advice does not become free simply because it was not separately invoiced, and proposed repricing requires evidence of client acceptance.
Can the buyer immediately move every CAS client to new software?
That depends on contracts, permissions, integration needs, and client readiness. Test export and import quality, preserve reporting continuity, and budget migration support. A platform change can affect workflows and client staff as well as the accounting firm. Plan the sequence before assuming that promised software savings begin at closing.
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.
- Client Advisory Services — CPA.com
- 2024 Client Advisory Services Benchmark Survey announcement — CPA.com
- Accounting firm profit and revenue: 2023 MAP survey — AICPA & CIMA