Practice

Client accounting services

Client accounting services, often shortened to CAS, are the ongoing accounting services a firm provides to a business client. They usually include bookkeeping, the monthly close, management reporting, payroll support and advisory work.

Reviewed November 3, 2026

Why it matters

CAS is a recurring relationship, not a one-time tax return. The monthly close creates a regular reason to ask the client for documents, review the numbers and stay involved through the year.

Example

A firm provides a monthly close, a profit and loss report, a cash forecast and a quarterly review for a growing service business. That is a CAS engagement.

Related terms

Questions about Client accounting services

How is CAS different from tax preparation?

Tax preparation is usually an annual engagement tied to a return. CAS is an ongoing monthly or quarterly service that keeps the books current and gives the owner regular reporting.

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Sources

Checked November 3, 2026. Public pages and tax rules change; confirm them before relying on them.

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