In Transcontinental Gas Pipeline Corporation v. Commonwealth, 153 Pa. Commw. 60, 620 A.2d 614 (Pa. Cmwlth.), aff'd, 157 Pa. Commw. 674, 630 A.2d 960 (Pa. Cmwlth. 1993), the taxpayer was an out-of-state business that sold gas to Pennsylvania customers. The taxpayer's rates for gas were subject to long-term contracts with its customers that were approved in advance by the Federal Energy Regulatory Commission (FERC), and not subject to change at the taxpayer's discretion. As a result, the taxpayer was required to anticipate and factor into its price all of the taxes that it would incur prior to submitting its rate request to the FERC because the FERC did not allow a taxpayer to recoup unexpected state taxes from its customers. The taxpayer did not file utilities gross receipts tax reports with the Department until notified by the Department to do so in 1975. The taxpayer had failed to file the reports on the mistaken belief that its sales were not subject to the tax under the "sale for resale" exemption contained in a former version of Section 1101(a) of the Tax Code, 72 P.S. 8101(a). From 1975 to 1984, the taxpayer filed the reports with the Department claiming the exemption, and received favorable reports for that period. However, the Department audited the taxpayer's report for 1984, and settled the report determining that the taxpayer owed $ 102,541.00 in gross receipts tax, and a penalty of $ 1,275.00, for gas that was not resold for the 1984 tax year. The taxpayer appealed the Department's resettlement to the Board, which denied the appeal. On appeal to this Court, the taxpayer alleged, inter alia, that even if it was subject to the tax, any change in its liability should only be applied prospectively. In disposing of this claim, the Court stated the following, in pertinent part: Because the taxpayer did not anticipate that it would become subject to the gross receipts tax before 1984, it did not incorporate this cost in its pre-1984 rate requests to FERC. Because the taxpayer received favorable reports since it began filing gross receipts tax reports in 1975, it is understandable that the taxpayer would continue to believe that its sales were exempt. Because we do not wish to impede or discourage the conduct of commerce, the gross receipts tax liability will be applied only from 1984 onward, the date the taxpayer had notice of the possibility that it was not exempt from the utilities gross receipts tax. The Department is thereby foreclosed from attempting to collect utilities gross receipts tax from the taxpayer before 1984. Accordingly, the orders of the Board of Finance and Revenue are affirmed as modified to apply only to prospective enforcement. Transcontinental Gas Pipeline Corporation, 620 A.2d at 621-622.