I was mistaken, have searched & found a definitive answer from Philip Steele of Octopus Energy: 'You can leave a smart tariff even if you’ve only been on it for a few days. We don’t block leaving a tariff. You just can’t start another smart tariff if on the previous one less than 30 days'.
& an explanation:
'We’ve recently made a change to how often you can switch between our Agile Octopus and Octopus Go smart tariffs. These tariffs offer customers the ability to unlock cheaper (and greener) electricity prices by using energy at particular times. They work best with that change in behaviour, and are designed for the long term.
For our fixed tariffs, we buy a customer’s energy for the 12 months ahead and price the tariff so that there’s a small margin for us to cover the costs of doing business. Our Flexible (SVT) tariffs follow the market more closely so can go up or down (but we’ll always give fair notice of any changes) and are bought in advance too, but for shorter periods..
Agile Octopus is designed to do away with all that: with prices based on the day-ahead wholesale market and charged based on what a consumer actually uses each half hour. Agile Octopus customers are then able to adapt when they use their energy, in particular avoiding peak times, to make significant savings.
We don’t hedge the consumption of Agile customers - ie. we don’t buy their energy in advance, The whole point is that prices reflect the current wholesale market. But we do hedge fixed tariffs (including Octopus Go). As such, if Agile customers switch to a fixed tariff, we then hedge their expected consumption - we buy it in advance at fixed prices. If customers then switch back to Agile, we’re stuck with having bought it according to standard consumption, but then paying for it according to the prevailing wholesale market every half hour.
So customers moving from Agile to fixed tariffs is ok, moving back the other way is harder for us.
Octopus Go is a great tariff with its off-peak rate of only 5p between 00.30 and 04.30, so it’s not surprising it’s seen as attractive. Octopus Go is hedged according to the expected consumption profile of a Go customer - that is, we buy your energy in advance for every half hour, based on our experience of typical Go customers. So if a Go customer switches back and forth between other tariffs, and changes consumption patterns, our hedging no longer works. So, as with Agile, we need to reduce the speed at which people can switch back and forth between Go and other tariffs'.
