(f)  Correct Pricing.  It is an unfair or deceptive act or practice for any person subject to 940 CMR 3.13 to charge a consumer an incorrect price for any item offered for sale.  The “correct price” is the lowest of:  the advertised price in any circular, newspaper, magazine, television or radio commercial, or in any other medium, or any published correction thereof; the price indicated on any store sign, shelf label, price tag or price sticker for the item; or the price rung up by the store’s automated retail system; provided, however, that the seller shall have no obligation to sell such item at the lowest represented price if it is the result of a gross error, if it is based on the price marked on another unit of the same item and the tendered item is marked only with a higher price, or if the price tag, label or sign shows evidence of obvious  physical  tampering.    A  “gross  error”is  a  price  which  was  never  intended  as  the  selling price at any time during the previous 30 day period, and which, for an item with an actual selling price of not more than $20.00, is less than half the price stated by the seller as the  actual  selling  price,  or  which,  for  an  item  with  an  actual  selling  price  of  more  than  $20.00, is more than 20% below the price stated by the seller as the actual selling price.  If these  provisions  for  establishing  the  correct  price  are  not  determinative  in  a  particular  situation, the correct price shall be the price on the seller’s current price list.   Sellers shall maintain a price accuracy and missing price report.  Whenever a consumer advises the store of an incorrect price on goods, signage, or register scanner, or that goods required to be price marked are missing such price marks, or that signs required to be posted are missing, or that a price is not in the register scanner, the store shall immediately fill out a price accuracy and missing price report with those details, and immediately correct the problem, making prompt payment to consumers who have been overcharged.  It shall be a complete defense in any action brought under 940 CMR 3.13(1)(f) that the seller has complied with the provisions of 940 CMR 6.13(2). (g)  Effective Date.  940 CMR 3.13(1) becomes effective December 15, 2003.