CAS practices reported a median growth rate of 17% in the 2024 CPA.com and AICPA PCPS benchmark survey, measured on calendar-year 2023 data. That number is why client accounting services keeps landing on partner agendas.
What gets less attention is that the same work runs under a different rulebook than the tax and audit engagements sitting beside it, and one of those rules stops being automatic at the end of 2026. Here is what the service covers, what a practice earns, and what has to be true inside a firm before it sells one.
What Client Accounting Services Actually Covers
Client accounting services is recurring accounting work a firm performs for a business client as an ongoing service rather than an annual deliverable. The firm holds the books, closes the month, and produces the reporting the owner uses to run the business.
The acronym drifted. Some firms read CAS as client accounting services, some as client advisory services, and some write CAAS to cover both. The benchmark survey the profession compares itself against is titled the client advisory services survey, and it treats the accounting work and the advisory work as one spectrum rather than two departments. Pick one label and use it consistently in engagement letters, because the words in the letter matter later.
The deepest form of the service has a precise working definition. The 2024 survey defined outsourced accounting as services for clients where the CAS practice serves as primary accounting or finance staff, meaning the firm has replaced the majority of the accounting department and accounting function for the client (2024 CPA.com and AICPA PCPS CAS Benchmark Survey).
The practical test is not the task list. It is the cadence and the seat. If the work arrives every month instead of every April, and if the client's controller function sits inside your firm rather than inside theirs, you are running a client accounting services engagement, whatever the invoice calls it.
The Four Layers, and Which Ones Pay
Most of the revenue is still in the bottom two layers, not the advisory tier the category is marketed on.
Survey respondents reported offering transactional accounting (97%), controllership services (90%), CFO services (69%) and business insights services (61%). The revenue split runs the other way. More than 65% of reported CAS revenue came from the transactional accounting and controllership categories, and 39% of firms said they do not offer business insights services at all (CAS Benchmark Survey).
Transactional accounting. Coding, bank and card feeds, payables, receivables, payroll input, and the reconciliations that make a trial balance worth trusting. This layer decides whether anything above it is worth reading, and it standardizes harder than the rest, which is why it survives a fixed monthly fee.
Controllership. The close, accruals, the review that catches a misposted item before it becomes a restated month, and the statements the client actually opens. This is the layer that consumes senior review time, so it sets how many clients one practice can carry before quality slips.
CFO services. Cash forecasting, budget against actual, pricing and margin work, lender and board reporting. Sell it as a named engagement with an owner and a fee, or it becomes unbilled work attached to the close.
Business insights. Strategic support built from financial and non-financial data, aimed at industry-specific problems and higher-level planning. It is real and thinly distributed, and building it means having something to say about one industry rather than every industry.
The order matters. A firm that sells the advisory tier before the transactional layer is reliable will spend its advisory hours fixing books.
What a CAS Practice Earns at the Median
Median annual CAS practice revenue was $1,606,409 across all respondents and $2,959,383 for the top-performing quartile. Median net client fees per professional reached $156,250, an increase of 29% over the 2022 survey, and median reported CAS revenue rose 61%. Respondents reported a median growth rate of 17% and projected 15% for the current year (CPA.com news release, survey report).
| Benchmark | All respondents | Top performers |
|---|---|---|
| Annual CAS practice revenue | $1,606,409 | $2,959,383 |
| Staff, full-time equivalent | 10.50 | 10.75 |
| Clients served | 69 | 102 |
| Source: 2024 CPA.com and AICPA PCPS CAS Benchmark Survey. |
Read the top-performer column with its definition attached. The survey classifies top performers as the top quartile by net client fees per professional, so any comparison on revenue per head is partly circular by construction. The survey adds its own caveat: in some cases practices that deliberately hire ahead of bringing on new clients are excluded from the top quartile, because the added full-time equivalents lower the ratio (CAS Benchmark Survey). What the column still shows is where the difference lands. The staff counts are nearly the same and the client counts are not, and the survey attributes that to technology, standardized processes, more defined strategy and larger clients rather than to a bigger bench.
Margin needs reading with care. The 2024 survey changed the question to margin before partner salaries or draws, defined as CAS gross revenue less direct staff costs, divided by CAS revenue. On that basis the median margin was 50%, and 55% for top performers. The survey itself warns that firms calculate the revenue and staffing inputs differently, and recommends treating margin as an internal trend line rather than a scoreboard against other firms (CAS Benchmark Survey).
One caution applies to every figure above. The survey collected calendar-year 2023 data from 206 CAS practices that self-selected to participate (CPA.com news release). Read the medians as a picture of firms already committed to CAS, not as a census of the profession. The next edition of the survey is due in December 2026 (CPA.com).
The Standard That Changes in December 2026
A CAS practice that produces financial statements has been applying AR-C section 70, the preparation standard. That stops being automatic once the new clarification takes effect.
The AICPA Accounting and Review Services Committee issued Statement on Standards for Accounting and Review Services No. 27, which excludes financial statements prepared as part of a consulting services engagement performed under CS section 100 from the engagements required to apply AR-C section 70. It takes effect for the preparation of financial statements for periods ending on or after December 15, 2026, and early implementation is permitted (CPA.com, SSARS standard clarification FAQ).
The test turns on the objective of the engagement, not on a disclaimer in the letter. If preparing the financial statement is the primary objective of the engagement, the work sits under the accounting and review standards and there is no election to make. If it is not the primary objective, if the firm is processing transactions and handling the controllership functions an accounting department performs on a fractional basis, the firm and the client may elect to run the whole engagement under the consulting standards instead. That choice can be made engagement by engagement, client by client, or across the whole CAS client base where the statement of work is standard (SSARS standard clarification FAQ).
The consequence is not cosmetic. "The practical difference for CPAs is that if they perform the engagement outside of AR-C Section 70, the quality management standards do not apply, and the engagements are not included in the population subject to peer review," said Mike Glynn, AICPA associate director of audit and attest standards, in the Journal of Accountancy.
What drops is the firm-level machinery, not the practitioner's duty. Under the consulting standards, quality and quality control rest on the practitioner's own judgment against professional competence, due professional care, planning and supervision, and sufficient relevant data, and the Code of Professional Conduct applies either way (SSARS standard clarification FAQ, Journal of Accountancy).
The old workaround does not hold either. The FAQ published alongside the change records the CAS task force's finding, drawn from discussions with standards experts, that an engagement letter simply stating the firm is not producing a financial statement is likely not adequate risk coverage when the client believes the CAS work will produce one (SSARS standard clarification FAQ). If it looks like a financial statement to the person receiving it, saying otherwise in a letter does not settle the question.
What this forces is a decision taken before the work starts about which standard the engagement runs under. A firm moving an engagement it currently performs under AR-C section 70 has to amend that engagement letter in writing (SSARS standard clarification FAQ). Firms that leave it implicit may find out which standard applied during a peer review year, which is the worst available time to find out.
The Independence Question CAS Raises That Tax Work Does Not
If your firm also audits, reviews or compiles the same client's statements, a CAS engagement is a stack of nonattest services, and the stack itself is the risk.
The AICPA Professional Ethics Division's nonattest services toolkit names financial statement preparation, cash to accrual conversions and reconciliations as nonattest services under ET section 1.295.010.06, with bookkeeping, payroll and other disbursements addressed at ET section 1.295.120. For a CAS practice those are not incidental services. They are the product.
The four things an attest client has to agree to before the work starts are set out in the general requirements at ET section 1.295.040, and they will be familiar from any documented bookkeeping engagement. The part that catches CAS practices is the list of management responsibilities at ET section 1.295.030, because an ordinary month of CAS work runs close to several of them: preparing source documents that evidence the occurrence of a transaction, having custody of a client's assets, authorizing or executing transactions on the client's behalf, accepting responsibility for the preparation and fair presentation of the financial statements, and accepting responsibility for designing, implementing or maintaining internal control (nonattest services toolkit).
A team that raises invoices, authorizes a payment run, or owns the design of the client's controls is doing work the code lists as a management responsibility, and the general requirements do not cure that. The list draws its line at authority, naming authorizing, executing or consummating transactions on the client's behalf, or having the authority to do so (nonattest services toolkit). The toolkit puts it plainly: a member may not assume management responsibilities, or even appear to assume them. It is equally explicit that scope, scale, frequency and duration all bear on whether services have become part of the client's internal control. Frequency is exactly what CAS changes. The same task performed monthly for three years reads differently from the same task performed once at year end.
Bundling adds its own test. Under ET section 1.295.020, before agreeing to perform nonattest services the member should evaluate whether performing multiple nonattest services in the aggregate creates a significant threat to independence that the general requirements cannot reduce to an acceptable level. A CAS engagement is multiple nonattest services by design, so that evaluation is the default case here rather than an edge case.
The decision this drives is easy to state and uncomfortable to enforce. Either the client keeps a real person, preferably in senior management, who understands the work well enough to oversee it and accept the results, or the firm gives up one of the two engagements. There is no version where the firm holds both and nobody at the client is accountable for the output.
Pricing: Hourly Billing Has Already Lost
Reliance on hourly billing among survey respondents fell from 53% in 2018 to 10% in 2024, and 84% are shifting to fixed fees payable monthly, quarterly or annually (CAS Benchmark Survey).
Fixed fees only hold with a change-order habit behind them. The survey's own caution is that practices on fixed fees need to reassess fees regularly and monitor out-of-scope work, because scope creep can cut into profits when staff at every level are not watching for it. Among respondents, 71% reevaluate CAS pricing annually (CAS Benchmark Survey).
Setup work is the piece most often given away. Among respondents, 79% charge a separate fee for new client onboarding, but only 55% charge separately for the technology, dashboard and application connectivity each client needs (CAS Benchmark Survey). That work is one-time and skilled, and it is not part of the recurring service, which makes it the clearest candidate for its own line.
Quoting a single monthly bookkeeping engagement is a separate exercise with its own inputs. At practice level the decisions are narrower: pick the fee model, write the change-order trigger into the engagement letter, and fix the date the fee gets reviewed.
Staffing a Practice Whose Work Never Stops
Seventy-eight percent of practices agree or strongly agree that their firm is committed to having dedicated staffing, an increase over previous surveys (CAS Benchmark Survey).
The reason to commit is structural. Tax capacity is seasonal and can be surged; a monthly close cannot be pushed to April. A practice that borrows tax staff for the close tends to lose the close in the weeks it matters most, and a missed close is the failure a client notices first.
The leverage in this data comes from technology and standardization, not from a bigger bench. Practices that strongly agree their firm is committed to continuous investment in technology report median net client fees per professional of $181,440 and a median of 100 clients against the all-respondent median of 67 on that same comparison (CAS Benchmark Survey).
Where the people come from is open in the data. Of respondents, 57% said all of their CAS staff live in the US and are employees of the firm or a subsidiary, 24% use offshore staff from non-subsidiary organizations, 9% use outsourced staff working within the US, 8% use both, and 12% have CAS staff in other countries who are all employees of the firm or a subsidiary (CAS Benchmark Survey).
Whichever route a firm takes, net client fees per professional is the number that governs the plan. At the median, $156,250 of net client fees is what one professional carries, and the survey calculates that figure with outsourced and offshore staff counted in the denominator (CPA.com news release, survey report). A growth target therefore converts into a hiring or sourcing decision before it converts into revenue. Recurring work needs a permanent seat, and a seat takes months to fill and train.
When a Firm Should Not Start a CAS Practice
Four situations where the honest answer is no, or not yet.
The firm cannot cover a close every month. Selling a monthly deliverable a firm can only produce in nine months of the year turns one capacity problem into twelve.
There is no niche and no intention to pick one. Firms reporting half or more of their CAS revenue from defined industry niches showed 38% higher median CAS revenue and 51% higher net revenue per client, while 29% of respondents still report no standardized processes, reporting or technology for any specific industry (CAS Benchmark Survey). Standardization is what makes a fixed fee profitable, and a niche is what makes standardization possible.
The real problem is tax season. CAS adds year-round load. It is a growth strategy, not relief for a compressed spring.
The target client is an attest client with nobody to own the work. The ethics analysis above closes that conversation before the commercial one starts.
Questions Firms Ask
Is Client Accounting Services the Same as Bookkeeping?
No. Bookkeeping is the transactional layer inside it. A CAS engagement usually adds the close, the reporting the owner reads, and some level of controller or CFO involvement, delivered on a recurring basis rather than as an annual cleanup.
Does CAS Stand for Client Accounting Services or Client Advisory Services?
Both labels are in use, and CAAS appears as a third. The benchmark survey firms compare themselves against uses client advisory services and treats the transactional and advisory work as one spectrum. What matters is that a firm uses one term consistently across its engagement letters and its fee schedule.
Can a Firm Provide CAS to a Client It Also Audits or Reviews?
Sometimes, and the analysis is harder than for a single nonattest service. Beyond the general requirements, ET section 1.295.020 requires evaluating whether the bundle in aggregate creates a significant threat the general requirements cannot reduce to an acceptable level (nonattest services toolkit). Work through it before the proposal, not after.
Does a CAS Engagement Have to Follow AR-C Section 70?
Not necessarily, for periods ending on or after December 15, 2026. Where preparing the financial statements is not the primary objective, a firm may elect to perform the engagement under the consulting standards instead. A firm converting an engagement it currently performs under AR-C section 70 has to amend the engagement letter in writing (SSARS standard clarification FAQ).
Where to Start
A CAS practice is a recurring-capacity business wrapped in professional standards. The revenue recurs by design, and the two things most likely to damage a firm are the two nobody writes down at the start: which standard the engagement runs under, and who at the client is accountable for the work.
Three decisions come before the first client. Pick the layers you will actually deliver and price the setup separately from the recurring fee. Decide which standard each engagement runs under, and amend the letter in writing wherever you are moving off AR-C section 70. Document the independence conclusion for any client whose statements your firm also touches.
Then solve the seat. Recurring monthly work needs people who are not borrowed from tax in April, and that is a staffing decision with a long lead time.
If your firm is carrying monthly work and the reviewer is the bottleneck, don't trust us, test us. Run a Free 40-Hour Proof Pilot on your own representative work, graded by your own reviewer, before a single client file moves.