More than a million customers of the Washington Gas Light Co. and Baltimore Gas & Electric will receive refunds of up to several dollars in the form of credits on their November bills.

The credits stem from a Supreme Court decision last May striking down a Louisiana tax imposed since 1979 on states receiving natural gas pumped through Louisiana pipelines from off-shore wells. Officials of eight states, led by Maryland Attorney General Stephen Sachs, argued that the tax was the equivalent of a duty charged by a foreign nation, and the high court agreed.

Washington Gas' 550,000 residential customers in Maryland, the District and Virginia can expect to receive credits averaging $6 if they are gas heating customers and $1.50 if they have nonheating service, according to spokesman Susan Betz.

An average credit of $3.42 will be applied to the bills of BG&E's 510,000 customers in Baltimore City and nine surrounding counties, including portions of Montgomery and Prince George's, according to utility spokesman John Metzger.

A second, smaller refund is expected sometime next year when investments made by Louisiana with some of the tax receipts mature.

Before the tax was thrown out, the Louisiana surcharge had cost consumers outside its borders between $200 and to $300 million. The tax actually was imposed on the gas pipeline companies, which passed along the cost to the utilities. They, in turn, charged the customers.