Ask most people what a CPA firm does and they’ll say taxes or audits. But one of the service areas driving significant growth inside accounting firms today is neither. It’s Client Accounting Services (CAS).
According to the AICPA and CPA.com Client Advisory Services (CAS) Benchmark Survey, firms with CAS practices reported a 17% median growth rate, significantly outpacing overall growth across the profession. Median CAS revenue increased 61% compared with the prior benchmark survey, while median net client fees per professional reached $156,250, representing a 29% increase.
The Numbers Behind Client Accounting Services
What CAS Actually Is
Client Accounting Services covers a spectrum from transactional bookkeeping support up through higher-level, CFO-style business insight — including cash flow forecasting, KPI monitoring, and financial strategy delivered through an ongoing, recurring relationship.
The AICPA’s own survey defines “outsourced accounting” within CAS as work where the practice functionally replaces the majority of a client’s internal accounting department.
Why the Growth Is Happening Now
Unlike compliance work, which is concentrated around fixed deadlines, CAS engagements are structured as ongoing monthly relationships — creating predictable, recurring revenue rather than seasonal spikes.
Firms report that standardizing processes and shifting to fixed-fee, subscription-style billing (rather than hourly, project-based pricing) is a major driver of the margin improvement showing up in the benchmark data.
Firms that treat CAS as a side offering, rather than a core growth strategy, are leaving a substantial and measurable revenue opportunity on the table relative to firms building it deliberately.
The Capacity Challenge Behind CAS Growth
Scaling a CAS practice runs into the same wall as scaling compliance work: it requires more skilled hands doing recurring, detail-sensitive bookkeeping and accounting work every single month, not just during a defined season.