Glossary
Client Accounting Services
Client accounting services (CAS) is a bundled offering where an accounting firm takes over a client's ongoing finance function — bookkeeping, payroll, reporting and controller-level oversight — as a single recurring engagement rather than separate billed tasks. It sits between outsourced bookkeeping and virtual CFO work, adding the interpretation and month-end ownership that pure bookkeeping does not include.
What sits inside the CAS bundle
Client accounting services is a packaging decision as much as a service decision — it takes work a firm might otherwise sell piece by piece and bundles it into one recurring engagement. The bundle varies by firm, but a typical CAS tier looks like this:
| Layer | What it covers | Who normally does it |
|---|---|---|
| Transaction processing | Bookkeeping, reconciliation, AP/AR | Bookkeeper |
| Payroll | Running payroll, filings, employee questions | Payroll specialist or bookkeeper |
| Reporting | Monthly financials, KPI dashboard | Senior accountant / controller |
| Review | Catching errors and inconsistencies before delivery | Controller or manager |
| Advisory touchpoint | A call to walk through the numbers | Partner or manager |
The bottom two rows are what separate CAS from plain bookkeeping. A firm that delivers coded transactions and a trial balance is selling bookkeeping. A firm that reviews the numbers, packages them into a report, and sits on a call to explain what changed is selling CAS — the client is paying for the finance function to be handled, not for a set of tasks to be completed.
Why firms move clients into the CAS tier
A client buying bookkeeping alone is one budget line the client can cut without much disruption — the transactions still get coded somewhere, even if it is a different vendor. A client whose payroll, reporting and month-end review all run through the same firm has far more switching cost, which is the real reason CAS commands a higher fee than the sum of its parts would suggest.
It also changes the shape of the relationship. A firm selling only bookkeeping talks to a client mostly through a query list. A firm running the full CAS bundle has a standing monthly conversation about the numbers, which is the natural setup for a CAS client to eventually ask for virtual CFO services — the bundle is often the bridge between compliance work and advisory work, not a separate line of business next to it.
Where CAS engagements get expensive to run
The review layer becomes the bottleneck. Every CAS engagement needs a senior person to check the bookkeeper’s work before it reaches the client, and that review does not scale the way bookkeeping does — a controller can only review so many clients’ numbers in a month. Firms that grow CAS past a handful of clients usually standardize the review checklist itself, so it takes the same predictable time on every client instead of depending on how thorough that week’s reviewer is feeling.
Payroll adds a compliance surface bookkeeping does not have. A missed filing deadline or a misclassified employee is a different order of problem than a late reconciliation — it carries penalties the client will notice. Firms running payroll inside CAS put it on the same tracked recurring workflow as everything else precisely because a payroll deadline cannot be the one that quietly slips.
The reporting layer eats senior time if it is rebuilt from scratch monthly. A controller manually assembling a dashboard in a spreadsheet every month is doing work that does not need a controller — the judgment is in reviewing what the numbers mean, not in formatting them. Firms that keep CAS profitable pull the numbers from a client profitability and realization layer that already tracks the figures, so senior time goes to the review and the conversation rather than the assembly.
Pricing the bundle without losing the margin
CAS is usually priced as one fee, which means the firm absorbs the cost of every layer whether or not the client uses all of it. The engagement only stays profitable if billing and scope are tied to what was actually agreed — a client who starts asking for extra reports or ad hoc reconciliations outside the original package is expanding the engagement for free unless someone is tracking scope against what the fee was built to cover.
The other lever firms underuse is tiering the bundle itself rather than selling one flat version of it. A client on the lower CAS tier might get monthly bookkeeping and a summary report; a client on the higher tier adds payroll, a management report with commentary, and a standing call with a manager. Written into the engagement letter up front, the tier structure gives the firm a clean upsell path instead of a single all-or-nothing price that either overcharges a simple client or undercharges a complex one.
How Uku handles client accounting services
Last updated September 19, 2026 Reviewed by Rain Allikvee
