Is Cosy Octopus worth it for heat pump homes after the April 2026 price changes?
By Matt · Published 10 May 2026 · Reviewed 6 June 2026
Last reviewed 6 June 2026.
Cosy Octopus is one of the more interesting Octopus tariffs if your home is heated mainly by electricity. It is built around the idea that a heat pump, electric boiler or electric radiators can do more work when electricity is cheaper, then ease back when the grid is under more pressure.
The April 2026 price-cap drop made the decision less obvious, and the July cap reset is another reminder not to treat Cosy as a normal default tariff. Octopus's smart tariffs still depend on regional rates, tariff terms, eligibility and the shape of your usage. A heat-pump home should not choose Cosy just because it sounds designed for heat pumps. It should choose it because the daily pattern fits.
How Cosy works now
Octopus describes Cosy Octopus as a three-rate smart electricity tariff for homes with a heat pump, electric boiler, electric radiator or similar electric heating. The useful pattern remains three Cosy Hours windows each day:
- 04:00 to 07:00 for early-morning heating and hot water.
- 13:00 to 16:00 for a midday top-up before the evening peak.
- 22:00 to 00:00 for late-evening heating, hot water or other flexible use.
Together, those windows give eight cheaper hours. The trade-off is the peak period from 16:00 to 19:00, when Octopus says the rate is above the normal day rate. That peak is the part that decides whether Cosy is a comfortable fit or a constant nuisance.
When Cosy is likely to suit a heat-pump home
Cosy is strongest when the home can move a meaningful share of heating and hot-water use away from 4pm to 7pm without getting cold. That usually means the heat pump is correctly sized, the home holds heat reasonably well and the household is happy to schedule around the tariff.
It may also suit homes where the afternoon window is genuinely useful. A 1pm to 4pm Cosy period can let the system lift the house temperature before the evening peak, rather than relying only on overnight heat. That is different from a simple EV tariff where the cheap window sits mainly at night.
Cosy becomes more interesting again if the home has other flexible loads. A battery, hot-water cylinder, storage heating behaviour or some appliance use can all make cheaper windows easier to use. The main point is still comfort first. A tariff saving is not useful if the house feels cold every evening.
When Cosy may be the wrong answer
A heat pump that needs to run steadily through the late afternoon and early evening can make Cosy awkward. Some homes lose heat quickly. Some people are home all day and want a stable indoor temperature. Some systems are not set up well enough to pre-heat gently without overshooting or using too much power.
Cosy also has to compete with the rest of the household. If you have an EV, a large battery, solar panels or unusual working hours, the suitable tariff may not be the one built around heating alone. An EV driver who can use Intelligent Octopus Go may prefer its overnight and smart-charging structure. A battery home may want Agile, Outgoing or Intelligent Octopus Flux checks. A low-use flat with electric heating may find a simpler fixed tariff easier to understand.
What the April and July 2026 price changes really mean
Ofgem's April to June 2026 cap was lower than the previous quarter for a typical direct-debit household on a default tariff. Ofgem has since confirmed a higher July to September cap. Those headlines can make specialist tariffs look urgent one month and less urgent the next. They do not automatically make Cosy poor or good value, because Cosy is not trying to behave like a flat default tariff.
The useful comparison is not simply Cosy against the national cap headline. Compare your likely Cosy usage pattern against a normal fixed or flexible tariff in your region. Include standing charges, any fixed-term or exit-fee details, how much use you can move into Cosy Hours and how much unavoidable use lands in the 4pm to 7pm peak.
Exact unit rates are deliberately not repeated here as evergreen figures. They vary by postcode and can change. Use the Cosy tariff guide and Octopus's live tariff page for current prices, then use the numbers for your region rather than a national average.
Separate the heat-pump quote from the tariff choice
Octopus's heat-pump pages now put a lot of emphasis on the Boiler Upgrade Scheme, including higher support for eligible oil or LPG homes. That matters for the upfront installation decision, but it is not the same question as whether Cosy is the best electricity tariff after the system is in.
Treat the quote, grant route, survey findings, radiator or pipework changes and cylinder space as one decision. Treat the tariff as a second decision based on your actual heating pattern, postcode rates and smart-meter setup. A subsidised installation can still be paired with the wrong tariff if the home needs too much power during the 4pm to 7pm peak.
The eligibility checks matter
Cosy needs more than an interest in heat pumps. Octopus says you need eligible electric heating, a smart meter it can connect to, half-hourly readings and acceptance of the tariff terms. The heating system does not have to be installed by Octopus, but Octopus still has to be able to read the meter and put the tariff on the account.
If you are switching supplier at the same time, leave room for meter setup and account checks. A smart meter that worked with one supplier can still need time to settle after a switch. If you are relying on Cosy for winter heating costs, do not assume the tariff will appear instantly on day one.
Billing evidence and heat-pump controls
The app, heat-pump controller, thermostat or home-automation dashboard can help explain what the heating system did, but Octopus's smart-tariff terms say third-party app data is not used for billing. Keep the bill, half-hourly meter data, tariff terms and any Octopus support messages as the main evidence if the account does not match the routine you expected.
It is also worth choosing one clear control route. If the heat pump, thermostat, battery, solar inverter and tariff schedule all try to optimise the same evening period, the home can end up fighting itself. A good Cosy setup usually starts with comfort, then uses the three cheaper windows to support that routine rather than chasing every cheap half-hour.
A practical decision checklist
- Heating pattern: can your home pre-heat before 4pm and stay comfortable until 7pm?
- Hot water: can the cylinder or heating controls use the cheaper morning, afternoon or late-evening windows?
- Regional rates: have you checked the actual Cosy rates and standing charge for your postcode?
- Other technology: would an EV, battery or solar setup point you toward a different Octopus tariff?
- Control comfort: are you happy managing schedules, or would a simple tariff reduce stress?
- Eligibility: do you have the right heating setup, smart meter and half-hourly readings?
- Billing evidence: can you check the bill and half-hourly meter data rather than relying only on an app screenshot?
Bottom line
Cosy Octopus is worth a serious look if your heat-pump home can use the three Cosy Hours windows without leaning heavily on the 4pm to 7pm peak. It is not automatically the suitable tariff just because you have a heat pump. The home, controls and household routine matter as much as the tariff name.
If Cosy looks like a good fit and Octopus still wins after you check live rates, the referral-code page explains how to start a switch through the referral route. If the timings do not fit, compare Go, Intelligent Go, Agile, Flexible or a fixed tariff before forcing the home around Cosy.