Essentials
You need
- A compatible electricity meter and a currently available product version for your region.
- Any required heat-pump eligibility or compatibility confirmed before switching.
Cheap heating windows built for heat pumps
Price now
25.51p
Typical
Next
12.52p
22:00 · Cheap
Today's cheapest
12.52p
04:00 · Cheap
Today's dearest
38.27p
16:00 · Expensive
| From | To | p/kWh |
|---|---|---|
| 00:00 | 04:00 | 25.508 |
| 04:00 | 07:00 | 12.517 |
| 07:00 | 13:00 | 25.508 |
| 13:00 | 16:00 | 12.517 |
| 16:00 | 19:00 | 38.267 |
| 19:00 | 22:00 | 25.508 |
| 22:00 | 00:00 | 12.517 |
The average is duration-weighted across the published time bands, so a two-hour band does not count the same as a six-hour one.
Explore the chart. Hover, focus or select any point to see its exact values.
Each month shows the version of Cosy Octopus you could actually have signed up to then, so the line follows the tariff through its successive versions rather than any one product code. Older versions carry on publishing rates for months after they stop selling; those are not averaged in, because nobody could buy them. Drawn from the stored daily rollups across every payment method the tariff publishes; where a tariff publishes more than one, the rates above show the direct-debit one and this line sits between them.
Choose a year above to see its prices.
Over 12 complete months, this tariff came in under the Ofgem cap in 3 of them.
| Month | This tariff | Cap | Difference |
|---|---|---|---|
| September 2025 | £65.31 | £67.94 | −£2.62 |
| October 2025 | £75.59 | £71.97 | +£3.62 |
| November 2025 | £73.15 | £69.64 | +£3.50 |
| December 2025 | £75.58 | £71.97 | +£3.62 |
| January 2026 | £75.80 | £75.18 | +£0.62 |
| February 2026 | £68.46 | £67.90 | +£0.56 |
| March 2026 | £75.79 | £75.18 | +£0.62 |
| April 2026 | £68.69 | £68.32 | +£0.36 |
| May 2026 | £70.98 | £70.60 | +£0.38 |
| June 2026 | £68.69 | £68.32 | +£0.36 |
| July 2026 | £70.98 | £73.69 | −£2.71 |
| August 2026 | £70.98 | £73.69 | −£2.71 |
Both columns cost the same 2,500 kWh a year on the typical household consumption pattern, on a direct-debit basis — the basis the cap itself is set on. A negative difference means this tariff was cheaper. The cap is a cap on what you can be charged, not a price anyone is billed, so this compares this tariff against the maximum a capped tariff could have charged the same household.
Before you switch
A quick suitability check before you compare the live price with your own home and usage.
Reviewed 24 August 2026
Essentials
Best fit
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Pairing
Make the final check
Current product version
COSY-22-12-08Regional tariff reference
E-1R-COSY-22-12-08-MDesigned for heat pump owners: three cheap windows a day, timed for efficient home heating. They cover a morning warm-up, an early-afternoon top-up and a late-evening stretch, and they are timed to match when heat pumps typically run. The trade-off is a sharply dearer early evening: Cosy's peak band is the dearest rate on the tariff by some way, so the saving comes from heating around it rather than through it. Heat pumps are already 3-4x more efficient than gas boilers, and combined with Cosy's cheap windows that can significantly reduce heating costs. The table on this page shows the bands actually in force today.