A gas bill usually includes a daily supply charge, the gas you used (often measured in megajoules, or MJ), and any discounts, concessions, fees or adjustments. Check the billing period, meter reading and whether the reading is actual or estimated, as an estimate can affect the next bill. Your retailer should show the rates that apply, payment due date and available payment assistance. If the bill seems unusually high, compare your usage with previous bills and contact your retailer; you can also check tariffs and concessions through your state energy authority or energy.gov.au.