What estimated meter readings mean on your bill

The fix is simple: take your own reading and send it in. Independent advice is to do this at least once a month, ideally on the same day each month, and the supplier must then base your account on the real figure⁴. This page explains how to tell an estimate from an actual reading, why estimates can build into a large unexpected bill, and what a smart meter changes.

What the 'E' on your bill actually means

When a supplier cannot take or receive a meter reading, it does not simply leave the bill blank. It produces an estimate: a figure derived from your billing history, usually for the same quarter or month, and from a database of similar properties³. Your bill will show 'estimated' or 'E' in front of the reading to flag that this has happened². National Energy Action puts the practical meaning plainly:

The estimate is not a random number, but it is also not your usage. If your circumstances have changed, perhaps a new appliance, more people in the home, or a house left empty for a stretch, the supplier's model has no way of knowing. That is why the marker exists: it tells you the bill needs checking before you pay it. The Energy Ombudsman's own guidance on reading bills says to look for an 'E' or 'estimate' to identify whether the reading has been calculated rather than taken⁷.

How to tell an estimated reading from an actual one

Bills carry codes next to each reading, and reading them takes seconds. The Centre for Sustainable Energy sets out the standard convention: an estimated read is marked 'estimated' or 'e', while a reading you supplied yourself, or one taken by a meter reader, is marked 'c' or 'a' for customer or actual⁸. Check the reading at the top and bottom of the billing period: if either carries the 'e' marker, at least part of the bill is a guess.

A few things to look for:

• 'E' or 'estimated': the supplier has guessed the reading²
• 'C' or 'A': a customer-supplied or actual reading, taken from the meter⁸
• An 'E' on a smart meter bill: the reading has been estimated, which suggests the meter may not be operating in smart mode at that moment⁹

One wrinkle worth knowing: even with a smart meter, a bill can occasionally be created on a day when the automated reading has not yet arrived. In that situation any difference between the estimate and your actual use is corrected on your next bill¹⁰. If you are unsure how the parts of a bill fit together generally, our guide to reading an energy bill goes through each section.

Why estimates turn into large unexpected bills

An estimate is only a problem when it drifts from reality, and drift is what happens when no reading is taken for months. If you are on a standard meter and do not send readings, you will most likely end up with an estimated bill, which means either over-paying or under-paying¹¹. Over-paying is recoverable; under-paying is the dangerous case, because the gap accumulates silently and then lands as a single catch-up bill. National Energy Action warns that estimated readings can lead to large unexpected bills, which is why it tells households to submit accurate readings regularly¹².

The Energy Ombudsman's case files show how this plays out. In one dispute, an account had been opened on an incorrect meter reading, which inflated the amount the consumer was asked to pay¹³. Estimated readings left the account running on figures that did not reflect actual use until a true reading was supplied and the account could be corrected. Meter exchanges add another layer: where a new meter starts at 00000 and the supplier is slow to update its records after the exchange, the account can continue to be billed on estimates that bear no relation to what the household has actually used.

The pattern in all of these is the same: the bill looked normal month after month, and the correction, when it came, was large. Regular readings, or a smart meter sending them automatically, keep the account anchored to what you have actually used. If a catch-up bill does arrive, the rules on back billing limit how far back a supplier can charge for energy in some circumstances.

Submitting a reading and getting the bill corrected

The process is short, and it works the same whether the estimate was too high or too low:

1. Read your meter, noting the main digits and ignoring any in red or marked off as fractions. Our guide on how to read a gas or electricity meter covers each meter type.
2. Send the reading to your supplier through its app, website or by phone. Uswitch's advice is to do this at least once a month, ideally on the same day of the month, such as the first⁴.
3. Ask for the bill to be recalculated. The supplier must base the account on the actual reading once it has one.
4. If the supplier refuses or stalls, complain in writing, then take the complaint to the Energy Ombudsman, whose dispute resolution service is free and independent⁶.

A few situations make a fresh reading especially important. If you are switching supplier, you will need to give your new supplier an up-to-date reading so it can calculate the actual credit you are entitled to¹⁵. If you have an older SMETS1 smart meter, you may need to send readings manually to get an accurate bill following a switch¹⁶. And if you are falling into energy debt, the recommended first step is to get a recent meter reading so your account is billed correctly and up to date before you negotiate anything else¹⁷.

Suppliers are allowed to estimate when they cannot take a reading, for example because they cannot get to the meter or because you have not given one in a while¹⁸. That right is not a problem in itself; the problem is estimates that go uncorrected. Submitting regular readings, or checking that a smart meter is sending readings correctly, is what keeps bills accurate¹⁹.

Smart meters: automatic readings mean bills are no longer guessed

A smart meter removes the main cause of estimated bills, which is the supplier not having a reading. Smart meters send gas and electricity readings straight to your supplier, so you get an accurate bill instead of an estimated one and do not need to submit readings yourself⁵. Ofgem's guidance lists the same two benefits: you do not need to submit meter readings yourself, and you get bills based on accurate meter readings and not estimates²⁰. Official guidance also notes that smart meters enable accurate billing by automatically recording energy use in half-hour periods²¹.

The practical effect, as SSEN puts it, is that meter readings are sent automatically, allowing for accurate bills, which should mean no more estimated bills or meter reader visits to your home²². National Energy Action's preparation advice makes the same point: with a smart meter, your supplier will no longer send you estimated bills and there is no need to provide readings yourself²³.

Two caveats apply. First, if a smart meter temporarily loses communication, your bills may become estimated again, you may need to take manual readings, and your in-home display may stop updating correctly²⁴. An 'E' next to a reading on a smart meter bill means the reading has been estimated and the meter may not be operating in smart mode⁹. Second, older SMETS1 meters may not communicate properly after a switch, so manual readings may be needed until the meter is updated¹⁶. Checking occasionally that readings are still flowing is the sensible habit¹⁹.

How estimated bills can leave households at risk

An estimated bill is a small but real dependence on your supplier's model of your home rather than on your home itself. The supplier guesses, you pay the guess, and the correction arrives later, sometimes months later and sometimes at a size that forces a difficult conversation about energy debt and repayment plans. The household that reads its own meter, or lets a smart meter do it, holds the one piece of evidence that settles every billing dispute: the actual figure on the dial.

That dependence is not evenly shared. Households on prepayment meters pay as they go and are not billed on estimates at all³. Smart meter households are billed on actual use in normal circumstances⁵. The exposure sits with standard-meter households who do not submit readings, and it is compounded for anyone whose supplier fails, where the reading record is what protects you with the new supplier¹⁴. It also reaches beyond the big suppliers: on heat networks, landlords and site owners are allowed to estimate if they cannot take a meter reading, and residents are advised to know how their bill is calculated¹⁸.

The remedy is always the same and always in the household's hands. A monthly reading, submitted on a consistent date⁴, keeps the account true, protects any credit balance when you switch¹⁵, and gives you the evidence to challenge any bill through the supplier and then, free of charge, through the Energy Ombudsman⁶. For a fuller picture of how readings and billing periods interact, see meter readings and estimated bills.