What is client accounting services (CAS), and what does a CAS team do?

Client accounting services (CAS) is a CPA firm's recurring outsourced accounting practice: bookkeeping, monthly close, payroll and bill pay, financial reporting and, at higher tiers, controller and CFO-level advisory work. Because CAS teams work inside clients' systems every month, they can spot companies with deep operational records, once ethics and independence rules are checked.

Client accounting services, defined

Client accounting services (CAS) is the part of a CPA firm that runs a client's accounting function on a recurring basis: recording transactions, closing the books each month, managing payables, receivables and payroll, producing financial statements and, at higher tiers, acting as controller or fractional CFO. Firms also call the same practice client advisory services, outsourced accounting or business advisory services.

What sets CAS apart from the rest of a CPA firm is continuity. Tax work peaks around filing deadlines and an audit happens once a year, while a CAS team is inside the client's ledger, bank feeds and approval workflows every month, usually on cloud accounting and automation tools the firm standardizes across its clients.

What a CAS engagement usually includes

Many firms package CAS into tiers with a fixed monthly fee, so the client buys an outcome rather than hours. Tier names and contents vary by firm; a common structure looks like this:

Tier	Typical services	Who does the work	What the team sees
Transactional	Bookkeeping, bill pay, invoicing, payroll processing, bank reconciliations	Staff accountants and bookkeepers	Bank feeds, vendor and customer lists, payroll registers
Controller	Month-end close, accruals, revenue schedules, financial statements, close checklist	Senior accountants and controllers	Contracts, job-cost and inventory reports, approval history
CFO and advisory	Budgets, forecasts, KPI dashboards, board packs, lender reporting, cash planning	CAS managers and CFO-level staff	CRM pipeline, operating metrics, leadership meetings
Specialty add-ons	Sales tax, entity management, software selection and implementation	Specialists	The client's full software stack

CAS vs similar services

Service	Provided by	Scope	Rules that frame it
Client accounting services	A CPA firm's CAS practice	Recurring accounting, close and advisory	The professional code and the state board's rules apply to the firm
Outsourced accounting	Accounting providers that may not be licensed CPA firms	Similar recurring work	Depends on who holds a license
Bookkeeping service	Bookkeepers or bookkeeping firms	Transaction recording and reconciliations	Mostly contract terms
Fractional CFO	An individual executive or a CFO firm	Finance leadership, strategy, lender and investor work	Depends on the person's licenses and firm
Transaction advisory services	A CPA or advisory firm's deal team	Quality of earnings, diligence, deal support	Professional rules plus the engagement terms

Why CAS teams notice clients with deep records

A CAS team sees how a client really operates. Across a year of month-end closes it learns which systems feed the ledger, which approvals happen in email or Slack, how far back the CRM goes, and whether the help desk, job-management or project tools hold years of closed work. That vantage point makes a CAS manager a good early judge of whether a client could license its operational records to AI developers, who need records of real multi-step work to train and test agents.

Signals that a client's records run deep:

The close checklist pulls from many sources: ERP or accounting, CRM, payroll, expenses, AP automation, inventory or project tools.
The company has operated for several years and kept archives when it changed software.
Workflows leave a trail of decisions and outcomes: approved and rejected quotes, resolved tickets, closed jobs.
Headcount reached 50+ full-time employees at peak (contractors excluded) at some point in its history.
An owner, CEO or CFO the team already meets could sponsor a licensing application.

The who qualifies page has the full baseline. The CAS team spots and introduces; it never exports, uploads or describes a client's records to SourceX, and the client works with SourceX directly on any inventory.

Ethics and independence checks come first

Before anyone at the firm raises a referral, check the professional rules. The AICPA's Commissions and Referral Fees Rule (ET 1.520) bars a member in public practice from accepting a commission for recommending a product or service to a client when the member or firm also performs an audit, review, certain compilations or an examination of prospective financial information for that client, and it requires permitted commissions and referral fees to be disclosed to the client, according to the AICPA Code of Professional Conduct. The Contingent Fees Rule (ET 1.510) is a separate restriction tied to the same attest relationships, as the New York State Society of CPAs explains. State boards can be stricter than the AICPA Code; the New Jersey Society of CPAs describes how its state's rules differ.

Which rule applies depends on how a payment is characterized and on every service the firm provides to that client, not only CAS. Work through these before any conversation:

Is the client an attest client of the firm, now or during any period the rules cover?
What does your state board's rule on commissions and referral fees say?
Does firm policy let partners or staff accept third-party referral compensation?
How will any referral compensation be disclosed to the client in writing?
Has the client agreed to its name being shared with SourceX?

This is general information, not legal, tax or financial advice. Confirm with your firm's ethics partner, your state board of accountancy or your professional body before acting.

How a CAS-led introduction works

Clear the ethics checklist and record the outcome in the client file.
Raise the idea with the owner or CFO at a natural point, such as a quarterly review, budget season or a planned systems change.
If the client is interested, register as a partner, then submit the company through the referral form or send the owner your referral link to apply.
SourceX qualifies the company with its sponsor on size, history, data breadth and rights.
The client completes a data inventory with SourceX, agrees price and terms, and decides whether to go ahead.

Partners earn 25% of the eligible platform fees SourceX actually collects from the referred company's licensing deals, capped at $100,000 per referred company, and nothing is payable until the buyer pays and SourceX receives its fee. That share comes out of SourceX's fee, never out of what the client receives.

Next step

Ask your CAS managers which clients' close checklists draw on the most systems, and screen the strongest with the company fit checker. Once the ethics checks are clear, register as a partner; the accountants partner page covers the wider firm playbook.

Step 1Share your linkSend your personal link to a company you know.
Step 2Company appliesThe company applies itself at /apply.
Step 3Buyer selects and paysThe buyer selects and pays for the data and SourceX receives its fee.
Step 4You get your rewardYour share of SourceX fees becomes payable.

Common questions

Is client accounting services the same as client advisory services?

Firms use both names for the same practice, and many keep the CAS acronym either way. Client accounting services stresses recurring accounting work such as bookkeeping and the monthly close, while client advisory services stresses forecasting, KPIs and CFO-level guidance. Most CAS practices offer both, with advisory work sitting in the higher service tiers.

How are CAS packages usually priced?

Many firms charge a fixed monthly fee per tier, scaled by transaction volume, number of entities, payroll headcount and the amount of advisory time included. Actual prices vary widely by market, firm size and client complexity, so compare scopes rather than headline fees.

Can a CPA firm accept a referral fee for introducing a CAS client to SourceX?

It depends on the rules that apply to the firm and that client. The AICPA Code bars commissions for recommending products or services to clients for whom the firm performs certain attest work and requires disclosure of permitted referral fees, and state boards can be stricter. Check with your firm's ethics partner and your state board before registering or introducing any client.

Does a CAS team share client data with SourceX?

No. The CAS team only makes an introduction and passes on basic fit information the client has agreed to share. The client deals with SourceX directly, completes its own data inventory, agrees redaction and de-identification rules before any work begins, and decides whether to sign. Nothing is delivered without an executed agreement and the client's authorization.

Which CAS clients are most likely to fit a data licensing introduction?

Established US clients whose workforce peaked at 50+ full-time employees, contractors excluded, with several years of operations recorded across CRM, ERP, support, project or engineering tools. B2B software, IT services, professional services, engineering and distribution businesses often fit. Clients whose records mainly belong to their own customers, or consist mostly of patient or consumer data, usually do not.

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By SourceX Partnerships Team · Published 2026-10-09 · Updated 2026-10-09

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