If your business has just received a back-bill for £18,000, been switched to a deemed rate three times normal market price, or discovered a broker uplift you never agreed to, you have legal options. UK business energy disputes follow a clear framework defined by Ofgem, the Energy Ombudsman, contract law and the Competition Act. Knowing the framework saves you months and almost always swings the outcome. This guide walks through the most common dispute reasons, the 56-day deadlock rule, your evidence checklist, a sample letter, and the escalation paths for both micro and non-micro businesses. Pair this with our business energy deemed contracts guide if your dispute is over an out-of-contract rate.
The most common UK business energy bill disputes in 2026
Roughly 65% of business energy disputes brought to the Energy Ombudsman in 2025-26 fall into one of seven categories:
- Back-billing: a sudden invoice covering 6 months to 6 years of “missed” usage. Ofgem’s back-billing rule limits supplier recovery to 12 months for micro-businesses where the supplier is at fault for not billing earlier.
- Deemed-rate uplifts: out-of-contract rates that can be 2-3× market rate. Often applied without the customer realising a fixed contract had ended.
- Wrong meter / wrong MPAN/MPRN: bill is for a meter that isn’t yours. Common in shared buildings and post-tenancy moves.
- Broker margin / hidden uplifts: a per-kWh broker fee added to the unit rate that wasn’t disclosed. Now a TPI Code obligation but still common pre-2024 contracts.
- Change of Tenancy (COT) errors: previous tenant’s bill assigned to new tenant, or vice versa. See our change of tenancy business energy guide.
- Switching errors: erroneous transfer (ET), failed switch, or supplier “objection” preventing a confirmed switch.
- Estimated reading wildly out: bill based on a placeholder estimate that’s 2-5× actual consumption.
Knowing which category your dispute falls into determines both the law that applies and the fastest escalation path.
Are you a micro-business? It changes the rules
Ofgem’s micro-business definition is the single most important question in any UK business energy dispute. Micro-businesses get free Energy Ombudsman access and stronger Standards of Conduct protection. Non-micro-businesses do not.
A “micro-business” under Ofgem rules is a non-domestic customer that meets any one of:
- Fewer than 10 employees (or full-time equivalent) AND annual turnover or balance sheet under €2 million (typically read as roughly £1.7-2.0 million in 2026).
- Annual electricity consumption under 100,000 kWh.
- Annual gas consumption under 293,000 kWh.
You only need to meet one of these to qualify. So a 12-employee solicitor with 60,000 kWh of electricity is still a micro-business by consumption. A 4-employee data centre with 250,000 kWh of electricity is a micro-business by headcount/turnover. Verify your status in writing with the supplier early in the dispute — suppliers occasionally challenge it to push you off Ombudsman protection.
The 56-day rule: deadlock letters explained
Under Ofgem’s complaint-handling standards (Standards of Conduct + Standard Licence Condition 7), a UK energy supplier must:
- Acknowledge a written complaint within 5 working days.
- Resolve it within 8 weeks (56 days), or issue a deadlock letter stating the supplier’s final position.
If 56 days pass with no deadlock letter or resolution, micro-businesses can escalate directly to the Energy Ombudsman. Non-micro-businesses must rely on the contract’s dispute clause and ultimately court action.
Two things to know:
- The clock starts when you send a written complaint, not when you call. Always log complaints in writing — email is fine.
- Suppliers will often offer “goodwill” credits during the 56 days to head off Ombudsman referral. These are not always full restitution. Compare against your worst-case calculation before accepting.
Evidence pack checklist
Before you put pen to paper, build a single PDF or folder containing:
- All bills covering the disputed period plus the 12 months before it. Annotate the lines you dispute.
- Meter details: MPAN (electricity), MPRN (gas), serial numbers, photos of the meter showing current reading and time/date stamp.
- Self-read history: any meter readings you submitted, with dates.
- Contracts: the original signed contract, any renewal notice, any “out of contract” notification.
- Letter of Authority: signed LOAs to brokers or third parties, dates and which suppliers they were used with.
- Correspondence: every email, letter, online chat transcript with dates. Suppliers can subpoena their own records but yours travel faster.
- Recordings or call notes: under UK rules, you can record your own calls if you are a party. Note the date, time, agent name and what was promised.
- Tenancy / company evidence: lease, completion statement or company registration if a Change of Tenancy is involved.
- Industry data: independent half-hourly data or DCC smart meter data if you have a smart commercial meter, to refute estimated reads.
The single most powerful evidence is a clean meter-read history that contradicts the supplier’s bill. If your reads are sparse, take a meter photo today (with date overlay if possible) and submit it as your “spot read” baseline.
Sample dispute letter (micro-business, deemed-rate dispute)
Adapt the following template to your situation. Send by email AND recorded post.
[Company name]
[Registered address]
[Date]
Complaints Manager
[Supplier name]
[Supplier address]
Re: Formal complaint — Account [account number] / MPAN [MPAN]
Dear Sir/Madam,
I am writing to formally complain about the unit rate and standing charge applied to the above account from [date] onwards. We confirm we are a micro-business under Ofgem’s definition because [we have fewer than 10 employees and turnover under £2M / our consumption is under 100,000 kWh / 293,000 kWh].
The disputed bill of £[amount] dated [bill date] applies a unit rate of [Xp/kWh] and standing charge of [£Y/day]. Our previous fixed contract ended on [date]. We did not receive a contract-end notification, and the deemed rate now applied is approximately [X]× market rate.
Under Ofgem’s Standards of Conduct and SLC 7, please:
- Acknowledge this complaint within 5 working days.
- Provide a copy of any contract end notification you claim to have sent.
- Apply a fair market rate to consumption from [date] until a new contract is agreed, or refund the difference.
- Issue a deadlock letter within 56 days if not resolved.
If unresolved, I will escalate to the Energy Ombudsman.
Yours faithfully,
[Name & position]
[Email] / [Phone]
Save the email’s read receipt, send a paper copy by Royal Mail Signed For, and keep both proofs of delivery.
Escalation paths
Path 1: micro-business → Energy Ombudsman (free)
After receiving a deadlock letter (or 56 days with no resolution), file with the Ombudsman:
- Free for the customer; supplier pays a case fee.
- Online portal at energyombudsman.org with the evidence pack as a single PDF upload.
- Decisions are binding on the supplier (up to £10,000 financial remedy in 2026).
- Typical resolution: 4-12 weeks from filing.
Outcomes that matter: financial credit/refund, an apology and corrective action, contract correction, or a directive to update the supplier’s processes.
Path 2: non-micro-business → contract dispute clause → court
If you exceed all three micro-business thresholds, the Ombudsman cannot help. Your route is:
- Internal escalation: senior account manager, then commercial director.
- Mediation: many supplier contracts include a mediation clause. CEDR or the CIArb panel are common.
- Arbitration: if the contract specifies it, follow that process.
- Court: County Court Money Claim (under £100k) or High Court (above). UK courts will generally interpret in favour of the customer where a deemed rate is “unconscionable” (3× market or more).
For larger users, the most powerful lever is the Competition and Markets Authority (CMA): if a supplier or broker pattern of conduct looks anti-competitive, the CMA route can outweigh any single contract dispute. Used sparingly.
Path 3: Ofgem Standards of Conduct breach
Independently of the Ombudsman, you can report a supplier’s behaviour to Ofgem if it appears to breach the Standards of Conduct (clear, fair, accurate, not misleading). Ofgem doesn’t resolve individual disputes but can fine and license-restrict suppliers for systemic breaches, which has knock-on effect on your case.
Broker disputes specifically
If your dispute is with a broker (Third Party Intermediary, or TPI), the framework is slightly different:
- The TPI Code of Practice (mandatory from 1 December 2024) requires brokers to disclose all commission, refer micro-business disputes to ADR, and respond within 8 weeks.
- Micro-business broker disputes can also go to the Energy Ombudsman via the Alternative Dispute Resolution (ADR) scheme.
- Non-micro broker disputes go via the broker contract’s dispute clause and ultimately court.
For full coverage of how brokers are paid and where margin is hidden, see our business energy broker fees explained and our UK business energy broker guide.
Practical wins to negotiate during the 56 days
Even if you win on principle, getting the resolution actioned costs time. During the 56-day window, prioritise these wins in negotiation:
- Bill credit and recalculation: the priority financial remedy.
- New contract on a fair fixed rate: most suppliers will offer a market-rate fix to retain you, especially if the alternative is Ombudsman referral.
- No early-termination fee: if your dispute is the supplier’s fault, demand the right to switch fee-free.
- Removal of any debt registration: ensure no adverse data has reached your business credit file. See credit score and business energy prices for why this matters.
- Goodwill compensation: £50-£500 typical for procedural failings; £1,000+ for serious customer detriment.
If you’ve resolved the dispute and now want a fairer market deal, run a free 60-second business energy comparison or call 0333 015 2615 to speak to a UK-based energy advisor.
Frequently Asked Questions
A micro-business under Ofgem rules meets at least one of: fewer than 10 employees AND turnover/balance sheet under €2M (~£1.7-2M); annual electricity under 100,000 kWh; or annual gas under 293,000 kWh. You only need to meet one of the three to qualify for free Energy Ombudsman access.
Under Ofgem’s Standard Licence Condition 7, suppliers must resolve a written complaint within 8 weeks (56 days) or issue a deadlock letter. After 56 days with no resolution or a deadlock letter, micro-businesses can escalate directly to the Energy Ombudsman.
For micro-businesses, Ofgem’s back-billing rule limits supplier recovery to 12 months of “missed” usage where the supplier was at fault for failing to bill earlier. Larger non-micro businesses are governed by their contract’s billing clause and ordinary contract law, with the Limitation Act allowing claims up to 6 years.
Build a single PDF containing all bills for the disputed period and 12 months prior, your MPAN/MPRN, meter photos with timestamps, your contracts and renewal letters, any Letter of Authority, every piece of correspondence, and a self-read history. Photographic meter reads are the most persuasive evidence.
No. The Energy Ombudsman covers domestic and micro-business customers only. Non-micro businesses must use their contract’s dispute clause, mediation, arbitration or ultimately court action.
From submission to decision, typical cases take 4-12 weeks in 2026. Decisions are binding on the supplier and can include financial remedy of up to £10,000 plus apology, contract correction and process change directives.
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