UK Energy Supplier Scores 2026: KT Score League Table

KT Score league table. Data to Q4 2025. Compiled 12 June 2026. Scored by data, not commission. See the KT Score methodology for the formula and sources.

The table below ranks five UK domestic energy suppliers by their Kael Tripton Score (the KT Score), a single figure out of 100 built only from published regulator and ombudsman data. The KT Score combines three inputs: Energy Ombudsman accepted complaints per 100,000 accounts (Q4 2025), the Citizens Advice customer-service star rating (Q4 2025), and Ofgem enforcement over the trailing 24 months to June 2026. Each input is normalised to a 0 to 100 scale, then weighted 45 percent, 40 percent, and 15 percent in that order.

The table orders suppliers by score. It draws no conclusion about which supplier any household should choose, because the figures are aggregates of complaint volumes and survey ratings rather than a forecast of one customer's experience. Price is not part of the score, since tariffs change each cap period. A higher score reflects fewer accepted complaints, a stronger customer-service rating, and a cleaner recent enforcement record across the published data; readers can weigh those components for themselves using the breakdown further down the page.

Every figure carries its source and publication vintage. Where a supplier appears in a regulator dataset under a licensee name that differs from its consumer brand, the licensee is recorded in the notes column.

The KT Score league table, data to Q4 2025

Complaints: Energy Ombudsman, Q4 2025. Rating: Citizens Advice, Q4 2025. Enforcement: Ofgem, trailing 24 months to June 2026. Enforcement reductions are detailed in the supplier notes below.

Sources for every cell: complaints from the Energy Ombudsman Disputes Data Q4 2025 pack, energyombudsman.org/complaints-data; star ratings from the Citizens Advice customer-service table, Q4 2025; enforcement from Ofgem investigations, orders and penalties, trailing 24 months to June 2026.

Supplier notes and licensees

How to read this table

The KT Score is a relative compression of three public datasets, not a verdict. A score of 80 out of 100 for Octopus Energy (KT Score, data to Q4 2025) means its combination of complaint rate, star rating, and enforcement record sits high across these specific measures this quarter; it does not mean the tariff is cheap or that a given household will have a smooth experience. The complaints column is the single heaviest input at 45 percent, so suppliers with far higher complaint rates, such as British Gas at 53.9 per 100,000 accounts (Energy Ombudsman, Q4 2025) and EDF Energy at 49.1 per 100,000 accounts (Energy Ombudsman, Q4 2025), carry that weight into a lower overall figure.

The enforcement column changes only when Ofgem documents a formal penalty, redress order, or enforcement decision inside the trailing 24 months. In this quarter three suppliers carry a reduction to 60 out of 100 on enforcement (Ofgem, to June 2026): Ovo Energy, after a Warm Home Discount redress of 2,765,200 pounds dated 22 January 2026 (Ofgem, 22 January 2026); Octopus Energy, after a prepayment final-bill redress of 1,483,000 pounds under an Ofgem decision dated 8 July 2025 (Ofgem, 8 July 2025); and E.ON Next, after a prepayment billing redress of 14,500,000 pounds published 20 November 2024 (Ofgem, 20 November 2024). EDF Energy and British Gas retain the full 100 because no qualifying action falls inside the window; older actions, open investigations, and compliance-review items are noted in the table but do not affect the figure.

The normalised components behind each score

The table below shows the three normalised metrics that feed the weighted average, each on a 0 to 100 scale. Metric A is the inverted percentile rank of complaints per 100,000 accounts (Energy Ombudsman, Q4 2025). Metric B is the star rating multiplied by 20 (Citizens Advice, Q4 2025). Metric C is the Ofgem enforcement value (Ofgem, to June 2026). The KT Score is round(0.45 A + 0.40 B + 0.15 C).

The component table makes the gaps legible. E.ON Next and Octopus Energy sit close on customer service, at 74.20 and 75.60 on the scaled rating respectively (Citizens Advice, Q4 2025), and the complaints percentile separates them: Octopus Energy at 90.00 and E.ON Next at 70.00 (Energy Ombudsman, Q4 2025). Both carry an enforcement value of 60.00 this quarter (Ofgem, to June 2026), as does Ovo Energy, whose mid-range complaints percentile of 50.00 (Energy Ombudsman, Q4 2025) and weaker scaled rating of 55.20 (Citizens Advice, Q4 2025) place its final figure at 54 out of 100, narrowly above EDF Energy at 49 out of 100, whose own figure is held down by a complaints percentile of 30.00 (Energy Ombudsman, Q4 2025) despite a full enforcement value of 100.00.

Where each number comes from

Three primary sources sit behind the table, and nothing else. Complaint rates come from the Energy Ombudsman Disputes Data Q4 2025 pack, which reports accepted complaints per 100,000 domestic consumer accounts for suppliers above one million accounts (Energy Ombudsman, Q4 2025). Customer-service ratings come from the Citizens Advice domestic supplier table for the same quarter (Citizens Advice, Q4 2025). Enforcement values come from Ofgem enforcement publications reviewed across the trailing 24 months to June 2026 (Ofgem, to June 2026). Each value is held in a deterministic scoring file with its source URL and vintage, so the league table can be regenerated unchanged from the same inputs. The full formula, weights, and renormalisation rule are set out on the KT Score methodology page.

Reading each supplier's figure

Octopus Energy records the highest figure in this quarter at 80 out of 100 (KT Score, data to Q4 2025), carried by the lowest complaint rate in the group at 20.0 per 100,000 accounts (Energy Ombudsman, Q4 2025) and the strongest star rating at 3.78 out of 5 (Citizens Advice, Q4 2025), tempered by an enforcement reduction for a July 2025 prepayment redress (Ofgem, 8 July 2025). E.ON Next follows at 70 out of 100, with a complaint rate of 22.6 per 100,000 accounts (Energy Ombudsman, Q4 2025), a rating of 3.71 out of 5 (Citizens Advice, Q4 2025), and its own enforcement reduction for a November 2024 prepayment redress (Ofgem, 20 November 2024). Ovo Energy sits at 54 out of 100, where a mid-group complaint rate of 24.3 per 100,000 accounts (Energy Ombudsman, Q4 2025) meets a January 2026 Warm Home Discount reduction (Ofgem, 22 January 2026). EDF Energy and British Gas record 49 and 38 out of 100 respectively, held down by complaint rates of 49.1 and 53.9 per 100,000 accounts (Energy Ombudsman, Q4 2025) and ratings of 2.60 and 2.28 out of 5 (Citizens Advice, Q4 2025). The figures describe published records for the quarter and are not a forecast of any individual household's experience.

When this table refreshes

The Energy Ombudsman and Citizens Advice publish their figures quarterly, and Ofgem publishes enforcement decisions as they conclude. This table will be regenerated when a newer quarter is available for the complaint and customer-service inputs, currently Q4 2025, or when an Ofgem action enters or leaves the trailing 24-month window, currently set to June 2026. Because the score engine is deterministic, regenerating the table from the same recorded inputs returns identical figures, and any movement between editions can be traced to a specific dataset update rather than a change in method.