Households with pre-paid gas and electricity meters are being urged to make sure they use their government relief vouchers.
The UK Government’s Energy Bill Support scheme will take £400 off bills across the winter, over six installments.
However, those on traditional prepayment meters need vouchers to get the discount.
The first ones, worth £66, were issued at the start of the October by post.
Some consumers may have received a text or e-mail, depending on their supplier.
But Advice Direct Scotland is warning people they only have 90 days to use the voucher after it emerged many have not yet been cashed in.
Just a third of users across the UK have used their voucher.
Colin Mathieson, spokesman for Advice Direct Scotland, said: “With the recent rise in energy prices, and more on the horizon, we know that many households are facing financial difficulties.
“Prepayment customers are often faced with self-disconnection when they can’t afford to top-up.
Check your vouchers
“Even in instances when they can top-up, this can cause severe financial hardship as they limit spending in other areas to do so, such as heating instead of eating.
“We would urge any households in Scotland who have a prepayment meter to check whether they have been sent a voucher and use it, and also to keep an eye out for the following vouchers when they arrive.
“Consumers should already have received their vouchers for October, if they have not, they should contact their supplier or Advice Direct Scotland’s advisers.”
Payments of £67 in December, January, February and March will follow the £66 payments for October and November.
Households with smart prepayment meters will be credited directly in the first week of each month.
The prepayment vouchers should arrive before the end of each month.
The charity also encouraged households to check their benefits entitlement, through its calculator at www.advice.scot to ensure they are not missing out on key support.
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