More than two million train tickets will be sold at a discount under a government scheme which begins next week.
Advance and off-peak tickets will be reduced by as much as half during a week-long sale starting on Tuesday for journeys across the UK between 17 January and 31 March.
The Department for Transport (DfT) said passengers saved about £5.8m during a similar promotion last year, where more than 600,000 tickets were sold, and that it had tasked rail firms to “deliver an even bigger sale” this time.
While it presents a potential saving for some customers, the sale comes less than two months before tickets on hundreds of routes are hiked by 4.6%.
A limited number of the reduced tickets will be available but will save customers who secure them considerable sums.
For example, a journey from London to Newcastle will fall from £52.10 to £23.60, according to the DfT.
The price of a journey from Nottingham to Manchester will be £9.20, while Glasgow to Inverness will cost £14.10.
The reductions only apply to advance fares, which are tickets which must be used on a specific service.
Most rail operators are participating, though Hull Trains, Lumo and Merseyrail are not.
The sale comes with regulated train fares in England set to increase by 4.6% from 2 March, while the price of most railcards will rise by £5. Unregulated fare rises are decided by train operators, but typically rise by a similar amount.
Around 45% of rail fares are regulated by the government in England, Wales and Scotland – but the rise only relates to travel in England.
No announcements on fare rises have been made yet by the Scottish or Welsh governments.
In October, the Campaign for Better Transport group said raising rail fares above inflation and increasing the cost of railcards was a “kick in the teeth” for people who rely on public transport.