Why does my AQ and SPC change annually?

Every year your gas usage is reviewed by the network provider, Gas Networks Ireland (GNI). GNI review your Annual Quantity (AQ) and Supply Point Capacity (SPC) to ensure you’re in the correct pricing group. The forecast AQSPC settings are implemented for the gas year, which runs from October – September.
You will find more information relating to this on Gas Networks Ireland website.