(1) This section governs the initial filing and implementation of a power supply cost recovery plan under section 6j(3).

  (2) The initial power supply cost recovery plan may be for a period of less than 12 months and shall be filed as follows:

  (a) By an electric utility subject to commission rate jurisdiction with at least 200,000 residential customers in the state of Michigan, by February 13, 1983.

  (b) By all other electric utilities subject to commission rate jurisdiction, by January 13, 1984 in accordance with the provisions of this act which the commission determines to be appropriate for the individual utility.

  (3) Notwithstanding section 6a(5), until the expiration of 3 months plus the remainder of the then current billing month following the last day on which a utility is required to file its first power supply cost recovery plan under subsection (2), the utility may alter its rate schedule in accordance with an existing fuel cost adjustment clause or purchased and net interchanged power adjustment clause. Thereafter, the utility may make charges in excess of base rates for the cost of power supply pursuant only to subsections (2) and (4). After October 13, 1982, any revenues resulting from an existing fuel cost adjustment clause or purchased and net interchanged power adjustment clause and recorded for an annual reconciliation period ending before January 1, 1983, by an electric utility are subject to the existing reconciliation proceeding established by the commission for the utility. In this proceeding, the commission shall consider the reasonableness and prudence of expenditures charged pursuant to an existing fuel cost adjustment clause or purchased and net interchanged power adjustment clause after October 13, 1982. On and after January 1, 1983, all fuel cost and purchased and net interchanged power revenues received by an electric utility, whether included in base rates or collected pursuant to a fuel or purchased and net interchanged power adjustment clause or a power supply cost recovery clause, are subject to annual reconciliation with the cost of fuel and purchased and net interchanged power. The annual reconciliations shall be conducted in accordance with the reconciliation procedures described in section 6j(12) to (18), including the provisions for refunds, additional charges, deferral and recovery, and shall include consideration by the commission of the reasonableness and prudence of expenditures charged pursuant to any fuel or purchased and net interchanged power adjustment clause in existence during the period being reconciled. If the utility has a lag correction provision included in its existing adjustment clauses, the commission shall allow any adjustment to rates attributable to that lag correction provision to be implemented for the 3 billing months immediately succeeding the final billing month in which the existing adjustment clauses as operative.

  (4) Until the commission approves or disapproves a power supply cost recovery clause in a final commission order in a contested case required by section 6j(2), a utility that had a fuel cost adjustment clause or purchased and net interchanged power adjustment clause on October 13, 1982 and which has applied for a power supply cost recovery clause under section 6j may adjust its rates under section 6j(3) to (18), to include power supply cost recovery factors.