In what is being dubbed the Great British Rail Sale, the UK Transport Secretary said more than one million train tickets would be reduced this spring.
The Department for Transport (DfT) is hoping the move will help hard-pressed households, facing rising bills and soaring inflation, to afford trips across the UK and boost domestic tourism.
The sale, said to be the first of its kind, with seats on some London to Edinburgh services being slashed from £44 to £22 and some Manchester to Newcastle journeys will go down to a little over £10.
This promotion currently only applies to the UK Department for Transport operators including LNER.
ScotRail has confirmed it is not involved with the project “at this time”.
However, the Scottish Liberal Democrats are calling for the Scottish Government to use its devolved powers to reverse the recent 3.8 per cent rail fare hike.
During this week’s opposition debate at the Scottish Parliament on Wednesday, the party will also urge the Government to expand railcard discounts so everyone can benefit from at least one-third off their ticket costs.
The motion argues both Governments have not used their powers enough to help struggling families during the cost of living crisis.
Alex Cole-Hamilton, leader of the Scottish Liberal Democrats, has criticised the current limited proposals put in place to tackle rising costs.
Both Governments, he said, are taking people “for granted” as both national insurance and council tax increases hit Scottish families.
Alongside rail fare cuts, the party is asking the UK Government to cut VAT to 17.5% – saving approximately £600 to to each family and reversing the national insurance increase.
The party has also urged the Scottish Government to announce protection for households experiencing council tax rises due to local council budget cuts.
Mr Cole-Hamilton said: “Scotland is facing the biggest fall in living standards since the ’50s.
“The current proposals set out by the Conservatives and the SNP do not go close to far enough.
“Both parties are taking people for granted; hiking national insurance, council tax and your train fares at the worst possible moment.”
The Scottish Government said they are committed to ensuring rail fares are affordable for passengers and taxpayers.
ScotRail fares are still, on average, 20% cheaper than those across the rest of the UK.
Transport Scotland is taking forward a Fair Fares Review to look at the range of discounts and concessionary schemes which are available on public transport.
A Scottish Government spokesperson said: “We know how challenging the cost of living crisis is for people who need to use public transport and are looking carefully at what more can be done to ensure passengers get the best value fare for their journey at all times.”
Under the UK Government rail sale, discounted tickets will go on sale from Tuesday April 19, with passengers eligible to travel for less on off-peak fares between April 25 and May 27.
Officials said offering half-price rail tickets was “one of the ways” the UK Government was helping to support families with the cost of living.