The rail regulator is to review the compensation regime between train operators and Network Rail (NR) amid claims that firms are "pocketing" tens of millions of pounds due to passengers for delays and cancellations.
The Office of Rail Regulation (ORR) said it wants to make sure compensation issues function effectively and do not disadvantage passengers or freight customers.
The ORR is also studying passenger awareness of their own compensation rights on questions such as how long they need to be delayed on a journey before they can reclaim their fare.
The Transport Salaried Staffs Association welcomed the news, following its claim last month that less than 10% of £184 million paid to private firms by NR for delays last year found its way back to passengers.
General secretary Manuel Cortes said: "The present compensation scheme is little more than licensed larceny by the private train operators.
"The passenger gets mugged twice, first when trains are delayed, and then when train firms are paid compensation for that delay via taxpayer-funded NR.
"But when passengers try to get their money back, they are told the train has to be two hours late to get a full refund. Rail firms get compensation when a train is more than five minutes late."