(1) A purchased gas adjustment (PGA) clause is an accounting and rate adjustment procedure that gas utilities use to recover actual gas costs. Gas utilities must file with the commission for recovery of expected gas cost changes and amortization of accumulated book balances.

(2) A gas utility must include its PGA procedures in its tariff.

(3) A gas utility must make a PGA filing within a maximum of fifteen months since the effective date of the utility's last PGA. If the utility believes that a PGA filing is unnecessary within this time frame, then it must file supporting documents within thirteen months after the effective date of its last PGA demonstrating why a rate change is not necessary.

(4) A gas utility must accrue interest, compounded monthly, on deferred gas cost balances which accrue subsequent to the effective date of this rule at the previous quarter's average prime interest rate calculated as follows: The arithmetic mean of the prime rate values published in the Federal Reserve Bulletin for the fourth, third, and second months preceding the first month of the calendar quarter (also known as the "FERC interest rate").

(5) A gas utility must file a monthly report of the activity in account 191, Unrecovered purchased gas costs, for Washington within thirty days after the end of each month. The report must show the beginning balance, monthly entry and ending balances for each Washington subaccount included in account 191, Unrecovered purchased gas costs. PGA incentive amounts must be shown separately.