From OpenCongress Wiki
Members of Congress are required to file reports detailing each gift of travel received from nongovernmental sources. Each report must list the source; the purpose of the trip; the estimated cost of travel, lodging, and food; the itinerary; and the dates of travel. If a spouse or family member accompanies the Member on the trip their covered expenses must be disclosed as well. Staffers must file travel disclosure reports and have them approved by their respective Member.
Travel reports are required to be filed with either the Clerk of the House or the Secretary of the Senate within 30 days of receipt of travel. Travel report disclosure rules are found in House Rule XXV and in Senate Rule XXXV.
Despite rules requiring public access to these reports neither the Clerk of the House nor the Secretary of the Senate place travel reports online on their respective websites. An amendment to the Senate Legislative Transparency and Accountability Act of 2007 sponsored by Sens. Norm Coleman (R-MN) and Ben Cardin (D-MD) requires the Secretary of the Senate to create an online database of travel reports. The House of Representatives must pass the bill for this measure to take effect. The website Open Secrets maintains a Congressional Travel Database that is free to the public.