12 C.F.R. § 715.4 – Audit responsibility of the Supervisory Committee.

(a) Annual audit requirement. A federally-insured credit union is required to obtain an annual supervisory committee audit which occurs at least once every calendar year (period of performance) and must cover the period elapsed since the last audit period (period effectively covered).
(b) Financial statement audit option. Any federally-insured credit union, whether Federally- or State-chartered and regardless of asset size, may choose to fulfill its Supervisory Committee audit responsibility by obtaining an annual audit of its financial statements performed in accordance with GAAS by an independent person who is licensed to do so by the State or jurisdiction in which the credit union is principally located. (A “financial statement audit” is distinct from a “supervisory committee audit,” although a financial statement audit is included among the options for fulfilling the supervisory committee audit requirement. Compare § 715.2(c) and (j).)
(c) Other audit options. A federally insured credit union which does not choose to obtain a financial statement audit as permitted by subsection (b) must fulfill its supervisory audit responsibility under either of § 715.5 or § 715.6 of this part, whichever is applicable. See Table 1. For purposes of this part, a credit union's asset size is the amount of total assets reported in the year-end Call Report (NCUA form 5300) filed for the calendar year-end immediately preceding the period under audit.
¹ The Supervisory Committee audit responsibility under part 715 can always be fulfilled by obtaining a financial statement audit. § 715.4(b).