Millions of households could save around £200 year by switching to a broadband social tariff.
But while take-up of these money-saving tariffs have quadrupled since January last year, the vast majority of those eligible still miss out, says Ofcom.
Research by the regulator has found that just 220,000 people are now signed up for these deals.
Social tariffs are available to an estimated 4.3 million households that receive one of a range of Government benefits.
These tariffs are cheaper and could slice the annual cost of broadband in half, which could be a major help during the cost of living crisis.
The packages offer super-fast speeds and a price freeze for the duration of the contract, for as little as £12 a month.
Yet awareness of these deals remains low, as 53% of eligible households are unaware of their existence.
Of eligible customers that are aware of social tariffs, most had heard about them through social media and TV.
But just 9% found out about social tariffs through their provider, with Ofcom saying this highlights that the industry needs to go further to promote their social tariffs effectively and make them easier to find.
Alongside consumer group Which? Ofcom says they are urging anyone on a Government benefit to contact their provider today to lock in a cheaper deal.
Lindsey Fussell, Ofcom's group director, network and communications, said: “We’re urging anyone who thinks they could be eligible for a discount deal to contact their provider today and potentially save hundreds of pounds.
"Providers should also do much more to help these customers find and access these deals, at a time when these savings could make a massive difference.”
Meanwhile, Matthew Upton, acting executive director of policy & advocacy at Citizens Advice, said: “Social tariffs put money back into people’s pockets. But as it stands, a shocking 95% of eligible households are together missing out on a £200 saving each year.
"That’s £824million of support going unclaimed."
“These latest figures show firms are still moving at a snail's pace. As they only have to offer these tariffs on a voluntary basis, they clearly aren’t incentivised to promote discounts.
"If this current rate of uptake continues, it will take 25 years before they reach everyone eligible.
“While we support the drive to raise awareness, the poor take-up looks like groundhog day. It’s time to question whether firms offering social tariffs on a voluntary basis really works.”
