California is the one state of the four with its own rule on practice sales. Board of Accountancy regulation 16 CCR §54.3, in force since April 1, 2024, requires a licensee who sells or transfers a practice and keeps no ownership in it to send each affected client a written notice by first-class or certified mail (or e-mail the client authorized in writing) asking for consent to transfer their records, with consent presumed after 90 days without objection. No records move before consent or day 90; records of clients who object are returned at once; records of clients who cannot be reached are not transferred and are kept for at least four years; the notice and every consent or objection are retained for four years after the sale. Closings are planned around the 90 days, and some agreements tie part of the price to consenting clients.
A firm that holds itself out as a CPA firm must be registered with the Board, so a buyer who is not a California-licensed CPA can take over a tax or bookkeeping book but not the CPA firm name. Bookkeeping needs no state license; non-credentialed tax preparers register with the California Tax Education Council (CTEC) and hold an IRS PTIN. Tax return information may be reviewed by a prospective buyer under a written confidentiality agreement without separate client consent (Treas. Reg. §301.7216-2(n)).
Sources: CBA regulations, 16 CCR §54.3 (PDF) · CBA approval notice for §54.3–54.4 · CTEC · 26 CFR 301.7216-2