Got the wrong bill from Octopus Energy? Here is how to fix it.
This guide explains who Octopus Energy is, the most common reasons your bill might be wrong, the law that protects you (especially the 12-month back-billing rule), and how to send Octopus Energy a proper complaint letter by Royal Mail.
About Octopus Energy Limited
Octopus Energy is now the biggest household energy supplier in the UK. They overtook British Gas in 2024, which is a really big deal because British Gas had been the biggest UK energy supplier for over 200 years (going back to the original British Gas Light Company in 1812). Octopus only started in 2015. They got big really fast by offering good prices, modern tariffs and online-first customer service. Today they serve over 7 million UK homes and about 12.9 million customer accounts when you count all their gas, electricity and EV services.
Octopus Energy was founded in August 2015 by Greg Jackson, who is still the CEO today. He was made a CBE in 2024 for his work in the energy industry, and joined the UK Cabinet Office board in 2025 as a non-executive member. The full company name for the supply business is Octopus Energy Limited (Companies House number 09263424). The head office is at 164-182 Oxford Street in central London. Octopus Energy Limited is owned by Octopus Energy Group Limited, which has raised over $2.3 billion from investors including Al Gore's Generation Investment Management.
Octopus runs a special technology platform called Kraken that handles all their customer accounts. Kraken is so good that other energy companies pay to use it — Origin Energy in Australia, Good Energy in the UK, EDF in the UK, and more. Octopus also has lots of different tariffs designed for things like electric cars (Octopus Go), heat pumps (Octopus Cosy) or smart meter customers who want half-hourly prices (Octopus Agile and Octopus Tracker). When billing goes wrong, it is usually because a complicated tariff or smart meter has not worked properly.
Registered office
Octopus Energy Limited164-182 Oxford Street
London (Westminster)
W1D 1NN
United Kingdom
Companies House number: 09263424 · Incorporated: 18 December 2014 · Parent: Octopus Energy Group Limited (Companies House 09718624) · Regulator: Ofgem (Office of Gas and Electricity Markets) · Ombudsman scheme: Energy Ombudsman (run by Ombudsman Services)
Group structure
Octopus Energy Group Limited (parent)
This is the holding company that owns Octopus Energy in the UK and lots of related businesses around the world. Founded by Greg Jackson on 5 August 2015 (it changed names twice: first Octopus Energy Limited, then Octopus Energy Holdings Limited, and finally Octopus Energy Group Limited in October 2020). It is now valued at around $9 billion and active in over 27 countries. Private company, not listed on a stock market.
Companies House 09718624.Octopus Energy Limited
This is the actual UK gas and electricity supplier holding the Ofgem licences. It is the company you have a contract with if your bills come from "Octopus Energy". The licences are for gas supply, electricity supply, gas shipping (NDM) and various electricity meter operator activities. If you need to take Octopus to court for an incorrect bill, this is the legal entity you serve.
Companies House 09263424. Ofgem-licensed supplier.Bulb Energy customers (the 2022 takeover)
If you used to be a Bulb Energy customer, you are now an Octopus Energy customer. Bulb went bust in November 2021 and was taken into a "Special Administration Regime" run by the UK government. In December 2022, Octopus took over Bulb's remaining 1.5 million customers. Migration finished by mid-2023. Some Bulb-to-Octopus migration bills have been a common source of incorrect billing complaints because old Bulb account data did not always transfer correctly.
Octopus Energy Services Limited (the installations business)
This is a different Octopus company (Companies House 10434397). It does installation work, like heat pumps and EV chargers. It is NOT the same legal entity as Octopus Energy Limited the supplier. If your complaint is about an installation (not a bill), the right legal defendant might be Octopus Energy Services Limited, not Octopus Energy Limited.
Common reasons your Octopus Energy Limited bill might be wrong
- 1The smart meter has not been sending readings. This is the biggest single cause of wrong bills. Octopus's system then bases the bill on an estimate, which is often too high (especially in winter) or too low. You can check by reading the meter yourself and sending it to Octopus.
- 2You were back-billed for more than 12 months. Octopus sometimes issues a big "catch-up" bill after an account was on estimates for a long time. The law (Standard Licence Condition 21BA) says they CANNOT bill you for energy used more than 12 months ago if the missed billing was their fault. This is explained in detail below.
- 3The wrong tariff was applied. Octopus has lots of tariffs (Agile, Tracker, Go, Cosy, Flexible, Loyal Octopus, etc). Sometimes a customer who is meant to be on a cheaper smart tariff gets billed on a more expensive default tariff. The difference can be hundreds of pounds a year.
- 4The Bulb migration mixed up your readings. If you were a Bulb customer who moved to Octopus in 2022 or 2023, your final Bulb reading and opening Octopus reading might not match. This causes consumption to be counted twice or missed completely.
- 5Direct debit went up without proper justification. Octopus has to give you fair notice and a clear breakdown if they want to raise your monthly payments. Big jumps that do not match your actual usage may need to come down.
- 6A previous occupant's debt was added to your account. If you moved into a new property, debts run up by previous occupants are NOT yours. You only owe Octopus for what YOU have used since you moved in.
The energy billing rules that protect you
| Rule | What it means | Source |
|---|---|---|
| 12-month back-billing rule | If your energy supplier did not bill you accurately because of their own mistake, they cannot now charge you for energy used more than 12 months ago. | Standard Licence Condition 21BA (domestic), SLC 7A (microbusiness). In force since 1 May 2018. |
| Standards of Conduct | Suppliers must treat you fairly, give you clear information, and make sure billing is accurate. | SLC 0 and 0A. |
| Priority Services Register | If you are vulnerable, you get extra protections including more regular meter reads. | SLC 26. |
| Default Tariff Cap | Limits the amount per unit and standing charge if you are on a default or "standard variable" tariff. | Reset every quarter by Ofgem. |
Octopus Energy Limited is signed up to all of these rules because they hold a UK gas and electricity supply licence from Ofgem. The back-billing rule (Standard Licence Condition 21BA) is the most important one for fixing wrong bills. It applies to every UK domestic energy supplier and has been in force since 1 May 2018.
The 12-month back-billing rule (your most useful protection)
Standard Licence Condition 21BA is the most powerful protection a UK energy customer has. It says: if Octopus Energy did not bill you accurately because of THEIR mistake, they cannot now charge you for energy used more than 12 months ago. The clock counts from the date of the first ACCURATE bill, not from when you first complained.
When does this apply? Common cases include: months of estimated bills followed by a big "catch-up" bill, a smart meter that stopped sending readings but Octopus did not notice, an account that sat unbilled after a transfer between suppliers, or a previous Bulb account that was not properly closed and reopened. If any of these match your situation, you can ask Octopus to write off the part of the bill that covers usage more than 12 months before the accurate bill date.
When does it NOT apply? If YOU prevented Octopus from billing accurately (for example, by refusing meter access, blocking smart meter installation, or refusing to give meter readings), Octopus is allowed to back-bill you for the longer period. The rule also does not stop them recovering the money for the most recent 12 months. So the goal is usually to argue for the bill to be CAPPED at the 12 months immediately before the first accurate bill, not to write the whole thing off.
Your rights
Standard Licence Condition 21BA (the back-billing rule)
This is the big one. Octopus Energy cannot bill you for gas or electricity used more than 12 months ago if Octopus was at fault for not billing accurately. The rule lives in the Standard Conditions of Electricity Supply Licence and the Standard Conditions of Gas Supply Licence, both made under the Electricity Act 1989 and the Gas Act 1986. It has been in force since 1 May 2018. If Octopus breaks this rule, they are breaking the terms of their Ofgem licence.
Standard Licence Conditions 0 and 0A (Standards of Conduct)
These set out broad rules about how Octopus has to treat you. They have to be fair, give you clear information, use plain language, and make sure billing is accurate. If Octopus behaves badly (rude staff, refusing to listen, confusing letters), they are breaking these conditions. Ofgem can fine them for it.
Standard Licence Condition 21B and 21BA (your bill must be accurate)
Octopus has to take all reasonable steps to base your bills on actual meter readings. If they only have estimated reads, they have to clearly mark the bill "estimated" and try to get an accurate read. If they have a smart meter that is sending readings, they must use the actual readings, not estimates.
Standard Licence Condition 31I (direct debit changes)
If Octopus wants to put your monthly direct debit UP, they have to give you fair notice and a clear breakdown of why. If your usage has not changed and your payments are already covering your costs, they cannot just put it up. Big unexplained jumps can be challenged.
Consumer Rights Act 2015, sections 49 and 51
This is the general consumer law that applies to all services in the UK, including energy. Section 49 says services must be performed with reasonable care and skill. Section 51 says the price must be reasonable if it is not agreed in advance. So if Octopus has charged you for a service they did not properly carry out (for example, wrong tariff applied), you can argue under this act.
How long do you have to challenge a bill?
The Limitation Act 1980 gives you 6 years to bring a court claim about a contract dispute in England, Wales and Northern Ireland (5 years in Scotland). But for an energy bill, you usually want to act much faster than that. Use the back-billing rule (SLC 21BA) and the Energy Ombudsman first. Court should be the last resort.
Common Octopus Energy Limited situations
You got a huge "catch-up" bill after months of estimates
This is the classic SLC 21BA case. If Octopus has been sending you estimated bills and then suddenly sends you a corrected bill for more than 12 months of usage, write to them quoting SLC 21BA. Ask them to cap the bill at the 12 months immediately before the corrected bill date. You only have to pay for that 12-month window. The earlier part has to be written off.
Your smart meter has not been sending readings
Smart meters sometimes lose their signal (mobile network issues, position in the home, technical faults). When that happens, Octopus's system uses estimates. The first thing to do is take a manual reading and send it to Octopus. If they have failed to spot the problem for many months and now want to back-bill you, you can use the back-billing rule. Octopus had a duty to notice and fix the smart meter problem; the back-billing rule does NOT only apply if you complained.
Your Bulb migration billing is wrong
If you moved from Bulb to Octopus in 2022 or 2023, your account may have inherited gaps or duplicates. The "Bulb closing balance" should match the "Octopus opening balance" exactly. If they do not, Octopus has to fix it. Quote the migration date and your Bulb account number. Octopus had to take over Bulb accounts as part of the government's Special Administration Regime, so they cannot say "it is not our problem".
You are on the wrong tariff
Check your tariff name on the latest bill. If you signed up for Octopus Tracker, Octopus Agile, Octopus Go or Cosy Octopus but are being billed on Flexible Octopus (the default tariff) instead, you are being overcharged. Send Octopus a letter quoting the tariff you signed up for and the dates. They have to put you back on the right one AND refund the difference, going back to when the error started.
Your direct debit went up sharply without explanation
Octopus has to follow SLC 31I when changing your direct debit. They must give fair notice and a clear breakdown of why. If your usage has not changed but your monthly direct debit doubled, demand a written explanation. Your credit balance, recent usage and current tariff should all line up with the direct debit amount. If they cannot justify the increase, ask them to put it back to the previous level.
A previous tenant's debt was added to your account
This sometimes happens during a property move-in. The previous occupant's debt should NEVER end up on your account. You only owe Octopus for energy used since you moved in. Send Octopus a letter with your tenancy agreement start date (or completion date if you bought the property) and demand the historical balance be removed.
Octopus is ignoring your complaint and refusing to fix it
After 8 weeks of no proper resolution, you can take the case to the Energy Ombudsman free of charge. The Energy Ombudsman makes binding decisions. If you do not want to wait, you can also go straight to the court using Money Claim Online. Either way, a formal letter sent first by Royal Mail makes both routes much stronger because it shows you tried to resolve directly first.
Send your Octopus Energy Limited complaint by Royal Mail
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Frequently asked questions
What is the back-billing rule and does it apply to Octopus?
Yes, it applies to every UK gas and electricity supplier including Octopus Energy. Standard Licence Condition 21BA says that if Octopus failed to bill you accurately because of their own mistake, they cannot now charge you for energy used more than 12 months ago. So if you suddenly receive a "catch-up" bill for 18 months or two years of energy, write to Octopus quoting SLC 21BA and demand the bill be capped at 12 months.
My smart meter stopped sending readings. Whose fault is that?
Smart meter signal problems are usually the supplier's responsibility. Octopus has a duty to monitor the data coming in and to fix problems they spot. If your meter stopped sending readings and Octopus failed to notice for many months, that is THEIR fault, not yours. You can use the 12-month back-billing rule. To be safe, you should also try to send manual readings whenever you spot a problem.
Do I have to take a credit balance refund as Octopus credit, or can I have cash?
You can have cash. If your Octopus account is in credit (you have paid more than you used), you can ask for the credit to be refunded to your bank account. Octopus's standard practice is to refund credit balances over £50 once a year, but you can ask any time. They have to give you the money — the credit is yours, not theirs.
What if I was a Bulb customer and my bills do not add up?
Bulb went into Special Administration in November 2021 and the customers were transferred to Octopus in late 2022/early 2023. The opening balance you had on Octopus should match the closing balance you had on Bulb. If they do not, Octopus must investigate and correct it. Quote your Bulb account number and the migration date in your letter.
How long do I have to make a complaint to Octopus?
There is no strict deadline for raising a complaint directly. But there are two important time limits in the background. The 12-month deadline applies for taking a case to the Energy Ombudsman: you have to escalate within 12 months of getting Octopus's final response. The 6-year deadline applies for going to court (5 years in Scotland) under the Limitation Act 1980. Acting sooner is always better because evidence is fresher.
How do I escalate to the Energy Ombudsman?
First make a formal complaint to Octopus in writing. They have 8 weeks to resolve it. If they refuse or you have a final "deadlock" letter, you can take the case to the Energy Ombudsman at energyombudsman.org or by calling 0330 440 1624. The service is free for customers and binding on Octopus. The Ombudsman can order Octopus to pay you compensation, write off charges, or apologise.
Will going to the Energy Ombudsman affect my account?
No. Octopus cannot punish you for using the Ombudsman. Your supply will not be cut off and your tariff will not be changed. The Ombudsman process is free, in writing, and usually takes a few weeks. Octopus is required to follow whatever decision the Ombudsman makes.
What can I claim if Octopus has clearly got it wrong?
You can claim several things. (1) Write-off of charges covering energy used more than 12 months ago. (2) Refund of any overpayments you made because the bill was wrong. (3) Goodwill compensation, usually £30 to £150 for distress and inconvenience, depending on how badly Octopus handled it. (4) Refund of any specific costs you incurred (for example, a private meter check you paid for, or interest on unnecessary debt). The Energy Ombudsman can award all of these.
Free help and what to do next
Energy Ombudsman
Free, binding dispute resolution for energy customers. After 8 weeks of unresolved complaint or a final response from Octopus, take your case here. Decisions are binding on Octopus. Free for you to use. Helpline: 0330 440 1624.
Visit website →Ofgem (the regulator)
The UK energy regulator. Does not handle individual complaints (that is the Ombudsman's job), but enforces the licence conditions including SLC 21BA. Worth reporting persistent bad behaviour by Octopus so it adds to their enforcement record.
Visit website →Citizens Advice Consumer Helpline
Free advice on energy bills, switching, fuel poverty support and consumer rights. Operated alongside Ofgem. Helpline: 0808 223 1133.
Visit website →Money Claim Online (MCOL)
The online court service for England and Wales. Use this if Octopus refuses to follow an Ombudsman decision, or to sue Octopus directly without the Ombudsman. You have 6 years from the date of the disputed bill to sue (5 in Scotland).
Visit website →Ready to challenge your Octopus Energy Limited bill?
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