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How the scores are worked out

This advice applies to England

We compare energy suppliers' customer service by looking at data from a number of reliable sources. We publish data about suppliers with more than 25,000 customer accounts.

Data about complaints to third parties

We base our ratings on complaints made to:

  • Citizens Advice Consumer Service

  • the Extra Help Unit

  • the Energy Ombudsman

Data about billing, customer service and switching

We use data from suppliers to determine the following:

  • Customer service - the average call centre wait time (excluding time spent in automated systems, and dedicated sales lines)

  • Bill timeliness - the proportion of bills and statements which are sent within 15 days of when they were due

  • Bill accuracy - the proportion of customers who got a bill based on a meter reading in the past year (excluding prepayment customers)

  • Switching - the proportion of switches completed within 21 days of the contract being agreed with the supplier

Data about customer guarantees

There is publicly available data on membership of the following schemes:


We also check with suppliers if they are certified for the British Standard for inclusive service provision (BS 18477) .

If we don't have data for your supplier

Suppliers are legally required to share the data we use in this rating. They also need to have a referral system to our consumer service.

If they don’t, we score them zero in categories related to these things.

We need suppliers to give us permission to publish data they share with us. If they don’t, you’ll only see a star rating.

How we come up with a star rating

We give energy suppliers a score out of 5 for each category. 1 is poor and 5 is excellent. Then we give them an overall star rating out of 5.

Category54321
Number of complaints per 10,000 customers 5 or less 5 to 15 15 to 30 30 to 55 More than 55
Average call centre wait time (seconds) Less than 30s 30s - 90s 90s - 180s 180s - 300s More than 300s
Switches completed within 21 days More than 98% 95-98% 90-95% 80-90% Less than 80%
Customers who had accurate bill in the past year
Bills and statements sent on time
Customer guarantees

Suppliers score 3 points for membership of the Energy Switch Guarantee, and one point each for membership of other schemes (up to a maximum of 5 points). Trial members of the switch guarantee score 2 points.

Not all categories are equal. Some, like complaints, count more towards the final score than others.

This is how we work out the overall scores.

CategoryMeasured asCounts towards overall score
Complaints to third parties Complaints to third parties 35%
Billing Bill accuracy 20%
Bill timeliness
Customer service Average call centre wait time 20%
Switching Switches completed within 21 days 15%
Customer guarantees Membership of a range of schemes 10%


To measure bill accuracy, suppliers must have been supplying more than 5,000 customer accounts for 12 months. Suppliers with less than this are scored on bill timeliness only.

Some suppliers have mostly customers who pay by prepayment. Suppliers with fewer than 5,000 billed customers do not receive a billing score, and are scored on the other categories only.

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