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Ofgem Standard Licence Condition 21B and the Back-billing Code

Complain to British Gas about a back-bill for energy over 12 months old

A bill for energy you used more than a year ago, with no warning, no readings? The Back-billing Code says they cannot do that. Quote it back at them.

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The law on your side

Ofgem Standard Licence Condition 21B and the Back-billing Code

Ofgem SLC 21B

  • The Back-billing Code prevents domestic suppliers charging for energy used more than 12 months before the bill was issued.
  • It applies to credit and direct-debit customers - not to deliberately bypassed meters.
  • The supplier loses the right only if you have not behaved obstructively and have provided meter access or readings when reasonably requested.
  • It applies to both electricity and gas supplied to domestic premises.

What you are owed

SituationRemedy
Charges over 12 months oldCannot be billed if you cooperated with reads
Refund of overpaymentsRecoverable for the same 12-month period
Ombudsman remediesApology, correction of bill, goodwill payment (typical range £30-£100)

Source: Ofgem SLC 21B. Figures are the published statutory amounts at the time of writing.

Copy-paste letter template

Replace anything in [SQUARE_BRACKETS] with your details. Keep the tone factual - the citations do the heavy lifting.

Dear British Gas Customer Service,

I am writing about my account [ACCOUNT_NUMBER] at [ADDRESS]. On [NOTIFY_DATE] I received a bill for £[AMOUNT] covering energy used between [PERIOD_START] and [PERIOD_END]. This bill is for usage more than 12 months old.

Under Standard Licence Condition 21B and the Ofgem Back-billing Code, a domestic energy supplier cannot seek payment for unbilled charges where the energy was supplied more than 12 months before the bill was issued, provided the customer has not behaved obstructively or unreasonably and has co-operated with reads. The rule applies to electricity and gas supplied to domestic premises.

I require:
1. A revised bill that excludes any consumption supplied more than 12 months before the date this bill was issued.
2. A refund of any direct debit payments already taken in respect of the back-billed period, where applicable.

Please respond within 14 days. If unresolved within 8 weeks, or following a deadlock letter, I will refer the complaint to the Energy Ombudsman, whose decision is binding on the supplier.

Yours faithfully,
[FULL_NAME]
[ADDRESS]
[EMAIL]
[ACCOUNT_NUMBER]
Personalise this letter with AISee all British Gas contact routes

If they ignore the first letter

  1. 1

    Write to the supplier

    Cite SLC 21B and the Back-billing Code. Ask for a revised bill that excludes consumption supplied more than 12 months before the bill was issued.

    Allow 14 days for a response

  2. 2

    Wait 8 weeks or get a deadlock letter

    If the supplier doesn’t resolve it within 8 weeks, or issues a final response (deadlock letter), you can escalate.

    8 weeks

  3. 3

    Energy Ombudsman

    The Energy Ombudsman is free for consumers and binding on the supplier. The supplier must comply with the decision within 28 days.

Final stop: Energy Ombudsman (binding decision).

Quick answers

Does the Back-billing Code apply to business customers?

Domestic and microbusiness energy customers are protected by SLC 21B and 21BA respectively. Larger businesses are not covered by the same rule.

What if I never gave them a meter reading?

The protection still applies, provided you weren’t obstructive and the supplier failed to send anyone for a reading or to estimate properly. The 12-month limit was designed precisely to make the supplier responsible for accurate billing.

How long does the Energy Ombudsman take?

Most decisions are issued within 6-8 weeks. The supplier has 28 days to comply if you accept the decision.

Which ombudsman does British Gas belong to?

The Energy Ombudsman, for anything to do with your gas or electricity supply. British Gas names it in its own complaints leaflet, along with the contact details: 0330 440 1624, enquiry@energyombudsman.org, or Energy Ombudsman, P.O. Box 966, Warrington WA4 9DF. Its service is free, and once you accept a decision British Gas has 28 days to carry it out. HomeCare is the exception and goes to the Financial Ombudsman Service instead.

What is the British Gas ombudsman telephone number?

0330 440 1624. That is the Energy Ombudsman, not British Gas, and it is open Monday to Friday, 8am to 6pm. Calls to 03 numbers cost no more than a call to an 01 or 02 number and usually come out of inclusive minutes. You can also email enquiry@energyombudsman.org or write to Energy Ombudsman, P.O. Box 966, Warrington WA4 9DF.

Should I report British Gas to Ofgem or go to the ombudsman?

Both, for different jobs. Ofgem regulates the market and states plainly that it has no direct role in investigating or resolving customer complaints, so reporting British Gas there helps it spot a pattern but will not resolve your case. The Energy Ombudsman is the one that can order British Gas to fix, apologise or pay, once 8 weeks have passed or you hold a deadlock letter.

How long does British Gas have to respond to a complaint?

Eight weeks to reach a solution, and its own leaflet says it aims to reply within two working days of a written or online complaint. Ask for it to be escalated and a complaints manager should come back to you within two working days. Once 8 weeks have passed without a fix, or a deadlock letter arrives sooner, the Energy Ombudsman will take it.

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Disclaimer: NoReply is an independent consumer advocacy platform. We are not affiliated with, endorsed by, or connected to British Gas. This page summarises Ofgem Standard Licence Condition 21B and the Back-billing Code (Ofgem SLC 21B) for general guidance and is not legal advice. Always check the current statutory text before acting.