More than a quarter of households do not know if they are on the most expensive standard variable tariffs (SVTs) for gas and electricity and around one in 20 do not know who supplies their energy, a survey suggests.
The poll for Bulb energy found 6% of people do not know who their supplier is, while 28% either do not know or are not sure if their household is on a poor value standard tariff.
This figure rises to 53% of 18 to 24-year-olds, while a relatively low 16% of 55 to 74-year-olds are in the same position.
The poll also suggests that households may be confused over whether they have switched away from SVT tariffs.
Some 44% said they had switched in the last year, but Bulb cited industry body Energy UK figures showing that 22% of the UK's 27.1 million households switched last year.
Bulb said it was surprised that half of the "most technically savvy generation" appeared not to know what type of tariff they were on, but said this could be due to 18 to 24-year-olds typically renting accommodation and mistakenly believing they were unable to switch, or inheriting prepayment meters at properties that often carry restrictions on switching.
Ofgem figures show that as of September the majority of customers - around 57% of those with the 10 largest suppliers - were still on poor value SVTs, around 13 million customers.
This is an overall reduction of two percentage points since last April.
Bulb said its survey suggests the Government should do more to engage young people into switching to better tariffs.
Hayden Wood, co-founder of Bulb, said: "Complicated tariffs and hard-to-understand bills mean 28% of all households don't know whether they're being ripped off or not. I'm particularly concerned that younger generations appear to be the most affected.
"This just shows why the Government must act to introduce a price cap as soon as possible to help families who are currently being taken advantage of by the Big Six."
:: Walnut Unlimited surveyed 2,016 UK adults online between December 20-22.