People who need to travel by train during lockdown are being urged to check journey planners as timetables are slashed.
Services are being cut from around 87% of normal levels to 72% due to the latest coronavirus lockdown in England.
Industry body the Rail Delivery Group (RDG) said this reflects the lower number of people travelling and provides better value for money for taxpayers, who are subsiding franchised train operators to keep trains running.
Morning and evening peak services are being prioritised to support key workers.
Some timetables have already been amended, while others will be changed over the coming weeks.
The RDG said alterations are being made in a way that will allow services to be restored “as quickly as possible when restrictions are eased”.
Leisure travel is currently prohibited, with people only allowed to leave home for limited reasons.
RDG director of nations and regions Robert Nisbet said: “Changing to a reduced timetable during this period of much lower demand will deliver certainty for those people who need to travel while saving taxpayers’ money.
“We ask people to check before they travel in the weeks ahead and we thank our frontline rail staff whose hard work is keeping other key workers moving.”
Rail minister Chris Heaton-Harris said: “It is critical that our railways continue to deliver reliable services for key workers and people who cannot reasonably work from home, and that they respond quickly to changes in demand.
“The new reduced timetable delivers that, as well as reducing the financial burden on the taxpayer.
“Levels of services will vary by operator and changes will come into effect steadily over the next few weeks.
“Passengers who are using the railways, including those who need to travel to vaccination centres, should check their route before they travel, and aim to do so outside of peak times wherever possible.”