How to Read a Gas and Electricity Bill

A domestic gas and electricity bill is built from two charges and one number. The two charges are the unit rate, how much is paid for each unit of gas or electricity used, and the standing charge, the daily fixed cost of supplying the home¹. The number is consumption in kilowatt hours (kWh), worked out from meter readings recorded on the bill². Everything else on the page, the tariff name, the account number, the meter serial number, the balance carried forward, exists to let a household check those three things.

Every domestic bill must carry a defined set of information: the customer's name and address, the supplier's name and address, the account or reference number, meter serial numbers, meter readings, usage over the last billing period, a breakdown of the current charges, tariff details including unit price and standing charge, contract details with any end date and exit fees, a tariff comparison rate, and a reminder of the right to switch³. The standing charge appears as a daily unit rate, with different prices for electricity and gas⁴. Where a household pays by credit meter, the regular bill shows tariff, unit price, energy usage, payments made and account balance⁵.

Two protections matter most when a bill looks wrong. Back billing rules mean a household does not have to pay for energy used more than 12 months ago where it has not had an accurate bill for that period⁶. Guaranteed standards set minimum service standards, with automatic compensation when they are breached⁷. Both are set by Ofgem and enforced through the supply and distribution licences.

Unit rate, standing charge and the meter details

The unit rate is the price per kWh. The standing charge is a daily amount that covers the fixed costs of providing the home with gas and electricity, including the network connection, meter readings, maintenance and government initiatives⁵. A household pays the standing charge whether or not it uses any energy, which is why a bill for a nearly empty property is never zero.

Behind those two figures sit the cost components Ofgem uses to calculate them: wholesale costs, network costs, operating, debt and industry costs, EBIT, policy costs and VAT, together with the type of energy used, the type of meter installed and how the bill is paid¹². A single bill does not itemise all of those, but they explain why two homes using identical amounts of energy can be charged different rates. More detail sits on what makes up a UK energy bill and policy costs and levies.

Standing charges also differ by region. Ofgem's benchmark maximum charges for 1 July to 30 September 2026 show the spread across electricity regions on single-rate terms¹³:

Those are cap benchmarks, not a quote for any one household. The point for bill reading is that a high standing charge in one region and a low one in another can sit alongside similar annual totals, because unit rates move in the opposite direction. Regional detail is covered in electricity and gas unit rates by region and standing charges.

The tariff name identifies which price list applies, and is what a household needs alongside annual usage or cost when comparing deals³. Tariff details can usually be found on the latest bill or statement, or in the supplier's app or online account¹. A dual fuel arrangement can be confirmed by checking whether a recent bill shows spending on both gas and electricity.

Consumption in kWh and what the meter readings show

The bill records gas and electricity meter readings, and those readings are used to calculate how many units of energy have been used². A supplier needs regular readings to work out bills, and will estimate usage where no readings are sent¹⁴. Estimation is the origin of most disputed bills: where suppliers do not receive readings they estimate based on how much energy they think has been used, which can lead to overpayment or to a large amount owed later¹⁵.

Not sending readings most often produces an estimated bill and therefore over-paying or under-paying, rather than any immediate loss of rights¹⁶. A smart meter removes the step: readings are sent automatically, and bills are based on accurate meter readings rather than estimates¹⁷. Households with prepayment meters do not need to take readings to be billed accurately, though tracking use can still be useful¹⁵.

Gas meters add one complication that a reader should expect: the meter records volume, and the bill converts that to kWh before applying the unit rate. The reading, the conversion and the resulting kWh figure all appear on the bill, which is what makes the arithmetic checkable. See how to read a gas or electricity meter and meter readings and estimated bills.

Back billing: the 12-month limit on charges for past energy use

A back bill is what a supplier asks a household to pay when it has not accurately charged for energy already used⁶. Ofgem's back billing rules mean a household does not have to pay for energy used more than 12 months ago where it has not had an accurate bill, statement of account, or where a Direct Debit was set too low⁶. The same limit is stated in Ofgem's consumer guidance on receiving a back bill¹⁸.

The restriction is a licence condition, not guidance. Ofgem's implementation work describes it as SLC 21BA, restricting suppliers from charging for energy used more than 12 months ago, with limited exceptions¹⁹. Independent consumer bodies describe the same rule from the customer's side: firms are banned from back billing for energy used more than 12 months before the error was detected where the supplier is at fault²⁰, and a supplier cannot usually send a bill for energy used more than 12 months ago²¹.

The rule also bites where estimates have gone uncorrected. It applies where a supplier has continued to send bills based on estimated readings even after accurate meter readings were sent²². A household that has been submitting readings and still receiving estimates is in the protected category, not outside it. A back bill can be challenged by writing to the supplier and making a formal complaint if needed²². The detail sits on back billing and how to complain about a back bill.

Where the 12-month limit does not apply

The limit is not absolute, and the exceptions are narrow but real.

• Unreasonable behaviour by the customer. A household will have to pay for energy used more than 12 months ago where it has acted unreasonably, for example by stopping the supplier from billing accurately, including by blocking access to the meter, ignoring requests for payment, or stealing electricity or gas¹⁸.
• A bill that was sent and not paid. The rules do not apply where the supplier sent a bill before the year passed and it was not paid; the supplier can still charge for it²¹. The same principle applies to heat: a bill sent within the time limit but left unpaid can still be charged even after 12 months has passed⁸.
• Charges outside the condition. In heat networks, charges recovered through a service charge are not covered by the 12-month back billing limit⁸.
• Non-domestic consumers. The back billing authorisation condition applies only to domestic and microbusiness consumers, so non-domestic consumers are not covered⁸. Ofgem's implementation consultation confirms that SLC 21BA on backbilling applies to microbusinesses, while the meter read requirement condition applies to all non-domestic consumers¹⁹.

The heat network guidance also sets out fault based exceptions in similar terms: where the consumer was obstructive in refusing a meter reading, where the consumer had a responsibility to provide a reading and did not, or where the consumer failed to manage or report faults, resulting in unpaid consumption.

When a bill is wrong, the supplier carries the responsibility

The starting point is that a supplier is responsible for making sure the meter works properly²³. Where there is a problem with a bill, the first step is to contact the supplier¹². Ofgem lists the issues a supplier should be contacted about: late, incorrect or missing bills, back billing, being overcharged, a faulty meter, poor customer service, and refusing to refund credit from an account²⁴.

Where a meter has been billing inaccurately, a supplier might only be able to charge for the energy used in the last 12 months²³. The exception to the back billing protection is narrow: it applies where the household has prevented the supplier from taking or receiving accurate meter readings²⁵.

Households that pay a landlord or site owner rather than a supplier are in a different position. Ofgem's guidance for those homes is that residents cannot choose their own supplier, cannot switch suppliers themselves, cannot complain directly to the energy supplier where they have no contract with them, and do not access all the protections available to domestic energy customers. They do have the right to see the bills and contract between the landlord or site owner and the energy supplier, and to know how the bill is calculated where the home has no meter.

Power cuts are the one bill related problem where the supplier is not the right contact: the gas or electricity network operator, not the supplier, is responsible for fixing power cuts and paying compensation¹¹.

How the limit works for direct debits and prepayment meters

Direct debit payments are usually based on an estimate of the amount of energy that will be used over a year²⁶, typically calculated from past energy use and spread evenly over 12 months. Payments will increase if more energy is used than the supplier has estimated²⁶, and a supplier should review a direct debit at least annually.

The back billing protection reaches into that mechanism. A supplier should not increase payments to cover the cost of energy used over 12 months ago²⁷. Where a debt falls inside the 12-month window, the supplier might increase payments and use the extra amount to pay off the amount owed over a few months²¹. That distinction, between clearing a recent shortfall and recovering charges from two years ago, is the one to test when a direct debit jumps. See why is my energy direct debit so high and how to challenge a direct debit increase.

Prepayment works the other way round. Prepayment customers pay in advance, before they use the energy, rather than paying by direct debit or paying bills after submitting readings²⁸. Because payment precedes consumption, a classic back bill is less likely, though it can still arise where the meter has been set to the wrong rate or where a debt recovery rate has been applied incorrectly. Related detail is on prepayment meters and repaying energy debt through a prepayment meter.

Guaranteed standards of service: who sets them and what they cover

Guaranteed standards set out minimum performance standards which all energy suppliers must meet, and when they do not, automatic payments are issued to the affected consumers⁷. Ofgem describes supplier guaranteed standards in the same terms: minimum supplier service standards, with consumers automatically compensated if they are breached¹⁹. For networks, the Guaranteed Standards of Performance specify what an electricity distribution network operator must pay a customer or relevant authority if it fails to meet specified standards of performance²⁹.

A distribution operator puts it plainly:

The network standards cover how operators respond to and deal with power cuts, and the service provided to people wanting to connect to the network³⁰. Gas standards cover restoring gas supply, reinstatement after works, notification of planned interruptions, connections, alterations and disconnections, provision of alternative cooking and heating facilities for priority domestic customers, and response to complaints.

In Northern Ireland the framework is separate but parallel: the electricity network operator, NIE Networks, and electricity suppliers all have guaranteed standards of service, and there are exceptions under which a company may not have to make a compensation payment in all instances³¹. See energy bills in Northern Ireland.

Ofgem is also consulting on extending the standards into smart metering, with new definitions planned for smart meter, in-home display, first time smart meter appointment and not operating as intended⁷.

Power cut compensation: the amounts and the thresholds

The amounts below are guaranteed standards payments made by the electricity network operator. Ofgem reviews and updates the amount paid for a power cut each year based on inflation³².

Ofgem gives worked examples for unplanned electricity cuts: a cut lasting more than 12 hours and interrupted for 36 hours attracts 2 additional £45 payments, adding up to £90, and a cut lasting more than 24 hours and interrupted for 72 hours attracts 4 additional £45 payments, adding up to £180³³. Ofgem's guidance states that an extra £45 is paid for every additional 12-hour period without electricity³², while the storm arrangements run on 6-hour increments¹⁰. Where a payment is late, an automatic payment should arrive from the network operator within 10 working days, and where it has not, making a claim should bring an extra £40 compensation¹¹.

Payments cannot be credited to an energy bill, because network operators do not have access to billing information held by suppliers. Unplanned cuts should be reported by calling 105 free of charge, which connects the caller to the electricity network operator³².

Storm payments arrive without a claim

For storm related cuts, eligible customers do not need to apply: payments are issued automatically by cheque once all affected power supplies have been safely restored¹⁰. The same operator sets out its wider guaranteed standards payment as £100 for domestic customers and £195 for non-domestic customers¹⁰.

Gas works the same way for loss of supply. Compensation for a loss of gas supply is paid through energy suppliers, appears as a credit on the next bill, and is paid automatically with no need to apply³⁴.

The practical implication for bill reading is that an unexplained credit line is not always an error. A credit that appears after a supply interruption may be a guaranteed standards payment passed through by the supplier, and it should be identifiable from the date of the interruption.

When no payment is due

Exemptions exist and they are written into the legislation. The legislation behind the guaranteed standards recognises exceptional events and allows exemptions to be applied, so no guaranteed standard payments would be due, for example where extreme weather conditions cause significant damage to the electricity network or create access difficulties³⁵.

Power cut compensation is also not paid for blackouts caused by a national power shortage, damage to electrical equipment or appliances, or a low supply after a power cut³².

Where a payment should have been made and was not, the Energy Ombudsman can act. Its case work records a further £30 awarded for failing to make the initial guaranteed standards payment within 10 working days³⁶. Its published principle is that where a company has not made the standard compensation payment, the Ombudsman will make an award that ensures the consumer is compensated in line with the regulations. The Ombudsman is an independent service, separate to Ofgem, for problems with an energy supplier, an energy broker, a network operator or a heat network supplier²⁴.

Ofgem's role when suppliers do not follow the rules

Ofgem monitors energy suppliers and network operators closely to make sure they meet the rules set out in licences, regulations and law, provide good customer service, and reply quickly to customers who contact them³⁷. Where it thinks a supplier or network operator has not met certain rules, it will start an investigation²⁴. It has the power to set fines for non-compliance, including for mis-selling, erroneous fees, complaints handling and slow rural electricity connections³⁸.

Ofgem has stated that it will be closely monitoring supplier compliance and will continue to take firm action against suppliers who fall short of their requirements. That enforcement, not the individual complaint, is what makes the billing rules on the page in front of a household more than a courtesy.

What a readable bill does, and does not do, for energy independence

A bill that can be read is the instrument of control a household has over a supply it does not own. The kWh figure is the only measurement of how much energy the home actually consumed; the unit rate and standing charge are the only measurements of what that consumption and that connection cost. Checking the two against each other is how overcharging, a mis-set tariff or a faulty meter is found.

What the bill cannot do is reduce dependence. The standing charge is payable regardless of consumption, so a household that cuts usage sharply still pays the daily fixed cost of remaining connected⁵. The unit rate is set by the supplier within the cap, not by the household. Even the guaranteed standards depend on a network operator identifying the affected supplies and issuing payment, and on the supplier passing gas compensation through as a bill credit³⁴. The protections described here are real, and they are all protections against a counterparty the household cannot leave. Reducing what is drawn through the meter is the only lever the household holds directly: see energy bills and energy independence and reducing an energy bill, and the pillar guide at /bills-price-cap/.