Movements on the wholesale markets have resulted in the reductions, according to the firm.
ScottishPower is to reduce customer bills for both gas and electricity, the supplier has announced.
From the end of March, gas plans are to be reduced in cost by an average of 7.5 percent. Meanwhile, electricity will also be cut by three percent.
The move follows the decision last month of British Gas to reduce its gas tariffs by ten percent. In both cases, the providers cited price trends on the wholesale energy markets as the reason for their bill changes.
These trends were also cited last year, when a commodities boom resulted in two separate rounds of price increases from all of the UK's "big six" energy suppliers. However, significant easing has occurred on the markets since last summer.
Willie MacDiarmid, ScottishPower's director of energy retail, said: "The past year has seen unprecedented volatility in the wholesale energy market and the future outlook remains challenging.
"Although wholesale prices have fallen recently, the market remains volatile … Against this backdrop we are working hard to protect our customers from this volatility and ensure that we offer the best possible value and service over the longer term."
