TL;DR
- Octopus Cosy is a three-rate electricity tariff aimed at heat pump homes, with two low-rate windows (4-7am and 1-4pm), a high peak (4-7pm), and a standard rate the rest of the time.
- Cosy only beats the Ofgem default tariff cap once a household actually shifts more than half of its heating load into the cheap windows. Below that threshold, the peak rate erodes the gain.
- Eligibility now requires a working SMETS2 meter and an air-source or ground-source heat pump declared on Octopus's account. There is no hard MCS certificate check at sign-up, but the account team will look at consumption shape.
- Cosy is electricity-only. Gas, where present, sits on a separate standard or fixed tariff.
- For April 2026, sample Eastern-region rates from the Octopus customer pages are 12.99p (off-peak), 27.49p (standard), and 39.96p (peak), with a 53.80p daily standing charge.
Last reviewed: May 2026
The cheap part of Octopus Cosy is not the headline 12.99p off-peak rate. It is the 1pm to 4pm afternoon window that lets a well-insulated home reheat the slab or charge a hot-water tank during the cheapest grid period of the day, then coast through the 4pm to 7pm peak with the pump throttled back. A heat pump household that cannot organise the day around those windows is, in practice, just paying a single-rate tariff with a punitive evening tax bolted on.
That is the framework anyone should use before signing up. The price points are public. The question is whether the load profile lines up.
Cosy is a tariff for households that can plan their day around their meter.
How the three-rate structure actually works
Octopus Cosy splits the 24-hour day into four price bands. Two are low. One is high. One is the standard daytime rate, which on the April 2026 publication tracks the Ofgem cap unit rate fairly closely. The off-peak windows are 4am to 7am and 1pm to 4pm, six hours in total. The peak window is 4pm to 7pm, three hours. Everything else is standard. The arithmetic of the tariff lives in those windows.
The pricing logic, set out on the Octopus tariff page on 1 April 2026, is to incentivise heat pump owners to lift consumption into periods when the wholesale market and grid carbon intensity are favourable. Early morning is cheap because demand is low. Early afternoon is cheap because solar is generating, especially during April to September. The evening peak is expensive because that is when the system is most stressed.
The catch is that the three-rate structure is fixed. It does not flex with day-ahead wholesale like Octopus Agile. A Cosy customer who shifts demand to the afternoon in midwinter is not necessarily catching low wholesale on that specific day; they are catching a contractual time-of-use discount. Most of the time those align. Cold high-pressure days, when wholesale spikes across the whole afternoon, are exceptions where Cosy is still cheap but Agile would not be.
Unit rates and standing charge by region, April 2026
Octopus publishes Cosy rates by Grid Supply Point region. The 14 distribution regions produce 14 slightly different price slates, mainly because standing charges vary. Below are sample rates pulled from the Octopus customer-facing tariff page on 1 April 2026, in pence per kWh inclusive of VAT.
| Region (DNO area) | Off-peak (p/kWh) | Standard (p/kWh) | Peak (p/kWh) | Standing charge (p/day) |
|---|---|---|---|---|
| Eastern England | 12.99 | 27.49 | 39.96 | 53.80 |
| London | 12.65 | 27.04 | 39.31 | 40.55 |
| South Wales | 13.18 | 27.85 | 40.44 | 61.92 |
| Yorkshire | 12.81 | 27.21 | 39.55 | 55.04 |
| North Scotland | 13.47 | 28.46 | 41.36 | 67.20 |
| South West England | 13.05 | 27.66 | 40.19 | 62.31 |
The North Scotland standing charge is the highest in the country because the regional distribution licence covers low-density geography. Cosy customers there pay roughly £245 a year before they have used a kilowatt-hour. London Cosy customers pay around £148. That gap matters when the discussion turns to small-flat heat pump retrofits.
The COP and SCOP arithmetic
A heat pump's coefficient of performance (COP) measures the heat delivered per unit of electricity consumed. Seasonal COP (SCOP) is the annual weighted average. A good air-source install in southern England on weather-compensation control can land between 3.2 and 3.8. A poorly designed install, with radiators left undersized and the flow temperature pinned at 55 degrees, can sit closer to 2.5.
That matters because the effective Cosy heat price is the electricity price divided by SCOP. At 12.99p off-peak and SCOP 3.5, useful heat from the pump in the cheap window costs roughly 3.71p per kWh delivered. Off the standard rate at 27.49p, it is 7.85p per kWh delivered. At peak it is 11.42p. Gas combi heating sits around 8p per kWh delivered when boiler efficiency and the Ofgem cap gas unit rate of 7.01p per kWh (Q1 2026 cap announcement, 22 November 2025) are combined.
So heat pump heat at the off-peak Cosy rate is roughly half the cost of gas. At the peak rate it is about 40% more expensive than gas. The whole exercise is moving as much heating load as possible into the cheaper bands.
What shifting load actually looks like in practice
Three behaviours move the most kWh into the cheap windows. A well-insulated home with a buffer tank or hot-water cylinder can heat during the afternoon window and coast through peak. A weather-compensated heat pump on a well-designed flow curve can run a longer, gentler cycle through the cheap hours rather than a hard reheat at peak. Time-of-use scheduling on the heat pump controller, set so the compressor backs off between 4pm and 7pm, captures the rest.
Modern heat pump controllers from Vaillant (Sensonet), Mitsubishi Ecodan (MELCloud), Daikin (Onecta) and Samsung all support a third-party time-of-use input. Octopus integrates with several of them via its smart-tariff API. Households without API integration can still hit the cheap windows by setting heating schedules manually.
The catch is hot water. Heat-pump hot-water reheat at 50 degrees can take an hour. If a household wants to bathe at 7am, the cylinder must reheat earlier. If it reheats at 6pm peak, the tariff math collapses. In practice many Cosy customers shift hot-water reheat into the afternoon window, then hold heat through the evening peak with cylinder insulation rather than reheat cycles.
How Cosy compares to other Octopus heat-pump-friendly options
Octopus runs several tariffs that intersect with heat pump consumption. Cosy is the dedicated one. Agile gives true half-hourly pricing. Tracker gives a daily-set wholesale-linked rate. Intelligent Octopus Flux is aimed at solar-plus-battery setups, not heat pumps. The relative position is worth setting out.
Against Agile, Cosy is more predictable but is ceiling-capped only by the standard rate during non-peak hours. Agile can offer sub-zero or even negative rates on windy nights, particularly in shoulder seasons, but exposes the customer to spikes. A homeowner with a battery storage system pairs better with Agile. A homeowner with just a heat pump and a hot-water tank usually does better on Cosy.
Against Tracker, Cosy is higher in the cheap window on most days but lower in the peak hour during stressed winter periods. The two suit different temperaments. Tracker's appeal is one daily price; the cognitive load is low. Cosy's appeal is structural shifting, where the heat pump and controller do the work.
Octopus removed the standalone Heat Pump Tariff in late 2024 and folded those customers into Cosy variants. Anyone still on the legacy fixed-rate heat pump tariff should check the active product code on their bill before assuming the rates above apply.
Eligibility, sign-up, and the practical pitfalls
To switch to Cosy, an Octopus electricity customer needs a working SMETS2 smart meter with half-hourly settlement active and a declaration of a heat pump on the property. The supplier is not running a hard MCS certificate check at the point of switching in 2026, but the account-team review will look at recent consumption patterns and may pause a sign-up where there is no clear heat-pump load shape.
The biggest pitfall is meter mode. A SMETS1 meter or a SMETS2 in single-rate mode cannot serve four price bands. Octopus typically arranges a remote re-commission of the meter to multi-rate mode before activating the tariff. In pockets of the country where the comms hub is on a weak signal, the re-commission fails and the customer is left waiting weeks for a field visit. Customers in old stone properties, basement flats, and parts of Cornwall and the Highlands have reported this most often, based on threads on the Octopus customer forum during winter 2025-26.
Most Cosy households recover from the meter delay within a billing cycle, but cold-weather mid-installs are particularly bad.
The other pitfall is exit. Cosy is a variable tariff with no exit fee. The standard tariff that customers default back to is Flexible Octopus, which sits at or near the Ofgem cap. Anyone planning to switch to a fixed product later in the year should keep an eye on the fix listings rather than expect to drop straight off Cosy into a discounted fix.
When Cosy is the wrong tariff
Cosy is the wrong tariff for households where heating load cannot be shifted into the cheap windows. That includes anyone whose home gets cold quickly without continuous heat (poorly insulated solid-wall homes that cannot hold a slab-charge profile), households where someone is at home in the evening peak using the immersion or running a tumble drier on hot, and customers without a smart heat-pump controller who would have to set schedules by hand twice a season.
It is also the wrong tariff for high evening cooking households. Three hours of induction hob and oven across the peak rate at 39.96p per kWh adds up fast. For a family that lives by an early-evening rhythm, the standard variable cap plus a separate dimmable strategy on the heat pump (lower flow temperature, longer runs through the day) tends to beat Cosy on net cost.
The customer profile Cosy serves best is the work-from-home or part-time household with a recent heat pump install, decent fabric performance, and a willingness to think about the day in three-hour chunks.
Sense-checking the install for Cosy compatibility
Before signing the contract, three install details determine whether Cosy will work for a given household. Flow temperature setting on the heat pump controller is the first; a system designed at 35-40 degrees flow can run long, gentle cycles in the cheap windows. A system stuck at 55 degrees flow cannot capture the same saving because every cycle is hot and short, which collapses the SCOP advantage.
Hot-water cylinder size is the second. A 200-litre cylinder gives enough thermal mass to reheat in the afternoon cheap window and hold heat through the evening peak. A 120-litre cylinder is borderline; a household with high evening hot water demand may need to reheat at peak rates, eroding the Cosy maths.
Heating zoning is the third. A household with thermostatic radiator valves (TRVs) and zone control can keep unused rooms cool overnight and reheat only occupied zones in the morning cheap window. This pairs especially well with Cosy because the early-morning band is short. Where there is no zone control, the whole house heats and cools together, which uses more kWh.
The Microgeneration Certification Scheme (MCS) installation report for a heat pump install typically records all three details. Customers should ask their installer for a copy of the MCS report before switching to Cosy and verify the design flow temperature, cylinder volume, and zoning approach align with how Cosy expects the system to behave.
Editorial disclaimer. Kaeltripton is an independent UK finance publisher. This article is general information for UK adults making their own decisions, not regulated financial advice. Tariff prices, cap levels, and supplier terms change. Figures reflect Ofgem and Octopus data dated before the last-reviewed date at the top of this page. Always confirm current rates with the supplier and read the full terms before switching. Where a complaint, refund, or vulnerable-customer protection is involved, the formal route runs through the supplier first and then the Energy Ombudsman.
FAQ
Is an MCS-certified heat pump required for Octopus Cosy?
Octopus does not run a hard MCS check at sign-up in 2026, but it does require an account-level declaration of the heat pump and will review consumption patterns. Boiler Upgrade Scheme grants do require MCS, so most recently installed pumps already have the paperwork on file.
Is gas central heating compatible with Cosy?
Cosy is electricity-only. If a household has gas, the gas sits on a separate standard or fixed tariff. The Cosy rates only apply to electricity consumption; gas bills are unaffected.
What happens to bills during the evening peak window?
Power used between 4pm and 7pm is billed at the peak rate (39.96p per kWh in the Eastern region for April 2026). A two-hour evening cook can add £1 to £2 to the day's cost compared to the standard rate. The tariff is still net positive if heating load is shifted to the cheap windows.
Does a low heat pump SCOP make Cosy uneconomic?
Probably. A SCOP under 2.7 makes Cosy marginal versus a standard tariff because the cost-per-kWh-delivered penalty in the standard and peak windows outweighs the off-peak gain. Get an updated SCOP estimate from the installer before switching.
How long does the switch onto Cosy take?
Existing Octopus customers can move within a few days once meter mode confirmation completes. New-to-Octopus customers typically take five working days under the Ofgem switching rules in force since May 2022, plus the meter mode confirmation if SMETS2 is not already operating in half-hourly mode.
Does Octopus update Cosy rates between Ofgem cap announcements?
Cosy rates change at Octopus's discretion, not on the Ofgem cap cadence. Cosy is a variable smart tariff; customers receive 30 days notice of material rate changes.