ScotRail has paid out more than £2,000 a day on average to passengers amid complaints of cancellations and delays.
The train operator gave travellers a total of £587,527 between April and December 2016.
Data obtained by Scottish Conservatives under Freedom of Information found the majority of the payments - £340,000 - were for delayed trains.
A further £178,000 was paid out in full or partial refunds to passengers who feel the agreed level of service was not reached while £52,000 was given as a "gesture of goodwill".
More than £10,000 was handed out in compensation over the nine months and £6,000 in refunds.
ScotRail handed money to passengers in 40,002 cases in the period.
December was the most expensive month, with a total of £98,878 claimed in 9,224 cases compared to 1,963 cases in April securing £24,244 recompense.
ScotRail has faced heavy criticism over cancelled and delayed services in the past few months and was ordered to put in place an improvement plan to bring performance in line with levels required by its Scottish Government contract.
Scottish Conservative transport spokesman Liam Kerr said: "It's no surprise the bill has surpassed £500,000 for the last nine months when you consider the problems on our railways.
"As well as passengers, you have to feel for the staff, who are doing their best with no help from the Scottish Government, and they will be wondering how transport minister Humza Yousaf ever allowed it to get this bad."
Earlier this week, ScotRail said its performance had improved but the yearly figure is still short of the Scottish Government target.
A ScotRail Alliance spokesman said: "We are completely supportive of Delay Repay because it compensates passengers for delays and our performance improvement plan is all about making our service punctual and reliable.
"We will continue to encourage passengers who've been delayed to claim back the portion of their ticket price that is rightfully theirs and have made the claiming process simple and speedy.
"Due to the ongoing investment and improvement of the railway network across the country, there have been more delays than normal and we're compensating customers as a result."
A Scottish Government spokeswoman said: "We acknowledge that there have been issues in respect of ScotRail's performance which has fallen below the standards required by the franchise contract.
"However, ScotRail has developed and implemented a performance improvement plan and we are encouraged to see that performance in this period is significantly better than the last, and above the same period last year."