The government has "massively overestimated" the number of people needing help with digital switchover, according to the Liberal Democrats.
Culture spokesperson Don Foster made the claim as the National Audit Office (NAO) published a report on the transition from analogue to digital television.
This is due to be completed by 2012 but one-third of the UK population do not fully understand they will have to purchase some form of digital equipment to continue receiving broadcast television.
A £603 million scheme run by the BBC has been set up to facilitate the process but the NAO report suggests the first switchover in Copeland shows the actual cost could be "significantly lower" than the ring-fenced amount.
Mr Foster, claiming up to £250 million of taxpayers' money could be left over, said progress on the scheme would come as "little comfort" to those left without jobs after the government's recent "tight licence fee settlement".
"Many of us were concerned at the use of the licence fee to fund this scheme in the first place. Now we need to know what will happen to the millions of pounds of licence fee payers' money that could be left over at the end of this," he said.
"The government must make a firm commitment to either invest the left over money back into public sector broadcasting or return it to the licence fee payer."
Today's NAO report expressed concern about the 26,000 analogue sets which need to be replaced or converted and nearly 1,200 transmitter sets which have to be upgraded.
NAO head Tim Burr said progress had been "encouraging" but added "there is a long way to go".
A government spokesperson said the start of the switchover seen in Copeland demonstrated "the effectiveness of the detailed plans we have put into place".