bert wrote:
My alarm bells start ringing whenever I see the word "savings".
Calculation of promised savings is defined by Ofgem and relate to the
amount you would pay if you stayed on your current supplier's standard
variable contract at the end of your current deal. Suppliers and
switching sites must abide by this rule. Claimed savings therefore are
not realistically achievable but purely as a comparator between one
offer and another.

That makes sense to me, because that's where you'd end up if you did
nothing. Your deal would end and you'd land on your supplier's variable
tariff. They should calculate based on the time you have left - eg you have
4 months of a fixed tariff plus 8 months of variable tariff if you did
nothing for a year, or 12 months of a new fixed tariff if you signed up
today. They do offer you new deals at your current supplier on the same
basis - ie the 'saving' isn't just for switching.

The 'saving' is thus based on your potential future trajectories, not what
happened over the last year. It isn't useful to compare against last year
because the wholesale price of energy when you signed up then is likely to
be different to now.

(similarly the saving can't account for changes in variable tariffs, which
would require predicting the future market)

Theo