When reading a gas bill, there are several items to check. Make sure that the name and supply address are correct, and you can check that the meter number on the bill is the same as the one on the meter at the premises. The MIRN (Meter Installation Registration Number) identifies the gas connection point – the premises – whereas the meter number identifies the physical meter, and would change if the meter ever needs to be replaced.
The supply charge consists of a daily fee, or tariff, multiplied by the number of days in the billing period. The tariff varies from retailer to retailer, and is not linked to how much gas you use.
This is the amount charged per megajoule (MJ) of energy used. The usage tariff might be the same for every megajoule, or it might change as you use more gas during the billing period – it used to be common for the gas to get cheaper as you used more, though this is changing as wholesale gas prices increase.
The gas bill shows the gas meter readings at the beginning and end of the billing period. It’s worth noting whether the meter readings were “actual” or “estimated” – they can be estimated, particularly if the meter is difficult for the meter reader to reach. The meter readings show the volume of the gas that has passed through the meter; the bill then shows a calculation of how much energy is contained in that volume of gas, which is worked out by multiplying the volume by the pressure factor or correction factor, and by the heating value (these figures are provided to the retailer by the gas distribution company).