From this Monday (January 23), the operator will increase the maximum fine for fare dodging to £100, reduced to £50, along with the original ticket price if paid within 21 days.
This change will replace the old penalty system of a £20 fine, or twice the full single fare to the next station.
Eleni Jordan, commercial and customer strategy director at Chiltern Railways, said: "It’s easy to buy a ticket either from Chiltern Railways' website, app, ticket machine or ticket office, so there are plenty of ways to buy a ticket. We are committed to enforcing the new penalty fare system against those who travel without a ticket.
"Fare evasion means there’s less money available to improve the railway for everyone. We hope that the new system coming into place on Monday will further deter those considering travelling without a valid ticket on our network."