The expensive mistake in a practice is made before the client signs
Accounting practices rarely lose money on clients they refused. They lose it on clients they accepted after quoting a fee against an impression rather than a scope. A prospect describes a small business with straightforward affairs, a partner quotes an annual fee from experience, and the practice then discovers three entities, two years of unreconciled records, an open assessment and a previous accountant who will not hand over. The engagement is now unprofitable for its entire life, and nobody will raise the fee because the relationship has already started.
Everything in this routine is arranged to prevent that. Scope before fee. Acceptance as a decision with recorded risk questions. Onboarding as a checklist with owners. And capacity understood as a calendar, because a practice that accepts a new client three weeks before a major deadline has committed to doing the work badly.