Back-billing rules for small businesses (microbusinesses)

Great Britain · Rules checked 24 October 2026 · Not legal advice

Free tool: Back-billing calculator. Enter the bill date and the period charged to find the 12-month line.

The back-billing rule (SLC 21BA) has applied to microbusiness consumers since 1 November 2018, on the same basis as households: a supplier can only charge for energy used, and standing charges built up, in the 12 months before the bill or other charge recovery action.

Who is a microbusiness?

The supply licence (SLC 7A) defines it by reference to the Redress Scheme Order 2008. Broadly, a business counts if it has fewer than 10 employees (or full-time equivalents) and annual turnover or balance sheet of no more than €2 million, or if its yearly use is low: up to 100,000 kWh of electricity or 293,000 kWh of gas. Check your supplier's definition if you're unsure.

How to use it

1. Find the bill date and earliest date charged; use the calculator.
2. Write quoting SLC 21BA (Part B, microbusinesses).
3. Complain formally if refused, then go to the Energy Ombudsman, which also handles microbusiness disputes.

The letters in the kit are written for households but can be adapted. Business contracts can contain extra terms, so get advice if large sums are involved.