220 CMR, 52.578
This account shall be charged at regular accounting intervals with that proportion of the unamortized discount and expense on outstanding bonds or coupon notes, which is applicable to the period. The proportion is to be determined according to a rule, the uniform application of which, during the interval between the issue and the date of maturity, will completely amortize or wipe out the discount at which such bonds were issued and the expense connected therewith. Such charges to this account shall not be greater nor less than the amount applicable to the period, so long as any portion of the discount and expense remains unextinguished. All or any portion of the discount and expense remaining at any time unextinguished may, at the option of the utility, be charged to account No. 416, "Discount on Bonds Extinguished through Surplus."
220 CMR, 52.578