Energy back-billing: when does the 12-month protection apply?
Understand GB household energy back-billing protection, old debt versus newly billed use, evidence to request and how to dispute a catch-up bill.
Quick answer
For Great Britain household gas and electricity, back-billing rules can protect against charges for energy used more than 12 months earlier that was not accurately billed or notified before. They are not a general write-off of old unpaid bills. Previous bills, account statements, meter access and the reason for the correction all matter.
GB household gas-and-electricity guide checked 25 October 2026. Northern Ireland, heat networks, landlord recharges and business cases need their own checks. A dispute should identify the protected charges rather than assume that the whole account balance disappears.
A corrected charge is different from an unpaid bill
Ofgem describes protection where old energy use was not accurately billed or notified through an account statement, including situations where Direct Debits were set too low. But if an accurate bill was issued and simply remained unpaid, its age does not make it disappear under this rule.
Ask the supplier to identify what was first charged now and what was already billed. A new document can contain both a correction and carried-forward debt. The printed issue date alone does not establish that every line is a new charge.
| Account item | Question to ask | Avoid assuming |
|---|---|---|
| Previously unbilled old use | When was it first accurately charged or notified? | Every catch-up charge is valid |
| Old accurate unpaid bill | Was this amount already correctly billed? | Debt is cancelled after 12 months |
| Current use | Are readings and tariff correct? | A past billing failure removes new charges |
| Payment balance | Have all payments and credits been included? | A higher Direct Debit equals a new energy charge |
Sources: Ofgem: back-billing protection and exceptions; Citizens Advice: old bills and unpaid debt distinction
The circumstances that can remove protection
Ofgem says the protection does not apply where a customer acted unreasonably, such as blocking meter access, ignoring payment requests or stealing gas or electricity. Do not assume an exception applies merely because a supplier says so: ask it to explain the conduct, dates and effect on accurate billing.
Keep records of readings you supplied, access offered, bills requested and replies. If you dispute the facts, make that clear in the complaint. Continue arranging payment for agreed current charges rather than treating a billing dispute as an instruction to stop every payment.
Sources: Ofgem: back-billing protection and exceptions; Energy Ombudsman: checking and disputing back bills
A worked 18-month catch-up example
Suppose a hypothetical bill dated 1 October 2026 newly charges £100 for each month from April 2025 through September 2026. Assume no earlier accurate bill or account notification and that all other protection conditions are met. The six months April–September 2025 total £600; the latest twelve months October 2025–September 2026 total £1,200.
The illustration separates £600 potentially protected old use from £1,200 recent use to review and pay as applicable. It does not erase an unrelated earlier accurate unpaid bill. Real daily cut-offs and charges must come from the supplier’s records, not this simplified monthly model.
| Period | Illustrative charge | Treatment assumed in this example |
|---|---|---|
| April–September 2025 | £600 | Outside the 12-month window; protection conditions assumed |
| October 2025–September 2026 | £1,200 | Within the window; accuracy still needs checking |
| Total newly charged | £1,800 | Not all automatically written off |
Request a reconciliation, not just a lower instalment
The Energy Ombudsman recommends checking the covered dates, amounts, deductions and meter-reading breakdown. Ask for a period-by-period explanation showing old charges reversed, replacement charges, payments received and any back-billing adjustment.
Illustration: an account shows a £1,800 new-use total, an agreed £600 protection adjustment and £900 of payments not yet reconciled. The remaining amount would be £300 if those payments genuinely belong against those charges and have not already been credited. Subtracting the same £900 twice would produce a false result.
- Current and previous bills and account statements.
- Dated actual and estimated meter readings.
- Tariffs and standing charges for each period.
- All payments, reversals and credits, counted once.
- The supplier’s written reason for applying or refusing protection.
Sources: Energy Ombudsman: checking and disputing back bills
Complain through the correct route
Raise a formal complaint with the supplier and keep the date and reference. State the disputed periods, the evidence and the correction sought. The Energy Ombudsman can consider eligible unresolved disputes after eight weeks or earlier deadlock; it provides an independent route rather than Ofgem deciding the individual bill.
If the remaining accurate bill is unaffordable, ask the supplier about a payment arrangement as a separate issue. A lower instalment can change timing without reducing the charge. Keep the back-billing decision and the repayment agreement distinct.
Sources: Energy Ombudsman: checking and disputing back bills; Ofgem: supplier complaints and Ombudsman route
Sources and worked-example method
Checked 25 October 2026. Original examples assume the conditions for back-billing protection are met, with no unreasonable customer obstruction. Flat monthly figures simplify the explanation; real corrections require dated meter readings, tariff periods, previous charges and payments. No personal liability decision is made.
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