If a business energy bill looks wrong, compare its dates, meter readings and rates with your contract and earlier bills. Write to your supplier with the disputed lines and supporting evidence, keep paying any amount you do not dispute if you can, and ask how to escalate the complaint.
Start with the paperwork
Check the billing period, supply address, meter serial or supply identifier, actual or estimated readings, unit rate, standing charge, tax and any credits. Compare these with your contract and your own readings. Write down what you believe is wrong and how you reached that view.
Raise a clear written complaint
Contact the supplier using its published complaint process. Include the account and bill reference, dates, readings, the specific charge in dispute, why you think it is wrong and what outcome you are asking for. Attach relevant bills and photographs of readings; keep the originals and copies of everything you send.
Ask the supplier to confirm it has logged a complaint and explain the next steps and expected response timing. Record names, dates and reference numbers for phone conversations, then follow up in writing.
If the bill arrives late
Ofgem's back-billing guidance says domestic and microbusiness customers generally cannot be charged for energy used more than 12 months earlier when the supplier did not bill them accurately, subject to exceptions. It is not an automatic cancellation of every old balance. Check the conditions and whether your business meets the microbusiness definition before relying on the protection; ask the supplier to explain how it has applied the rules.
If readings were unavailable because access was blocked or another exception may apply, explain the timeline and keep evidence. Do not ignore the bill; challenge it clearly and ask for a written decision.
Know where to get support
Ofgem directs microbusinesses and small businesses to Citizens Advice for energy contract support. If a supplier complaint remains unresolved, the Energy Ombudsman may be able to help eligible business customers; check its current eligibility requirements and complaint process. A dispute with a broker may follow a different redress route from a supplier complaint.
Keep a simple case file
Store the bill, contract, readings, complaint, supplier response and any advice in one place. Note important dates. A clear timeline can help you explain the issue to the supplier or an independent adviser.
The estimator can help check an indicative cost from known annual usage, but it does not verify bills, make a complaint or give legal advice.