It depends on your firm's policy, for example: - if the policy is phrased as "we'll pay as long as the client's not on the way to work" then Reading is definitely not on the route from Woking to London- if the policy is phrased as "we'll pay the difference in price between your regular commute to London and travel to client site" then Woking-Reading may be about the same as Woking-London (just guessing by straight-line distance - god knows how the rail pricing works)The issue may be whether you can claim for a season ticket instead of trip-by-trip tickets. Although it may be more expensive, separate tickets for each trip are more "accountable". You may therefore have to lay out the case step by step, e.g. the project is going to last at least the next 25 weeks, I have been committed to work with the client full-time on-site, a daily return ticket costs £10 (25 weeks x 5 days x £10 = £1,250), a six-month season ticket costs £1,000, therefore we save the client money and save ourselves the hassle of processing all these tickets through expenses.