The cost of running an MP's office, paying their staff, funding expenses and reimbursing travel can come to £250,000 a year.
There are significant differences between the business costs incurred by Wales' 40 MPs which largely reflects the distances they have to travel and the costs of their accommodation.
We've looked at the costs incurred by all of Wales' MPs which have just been published on the website of Ipsa, the independent body responsible for overseeing pay and expenses for elected Parliamentarians.
