The accounting complexity of the travel account is marked by the different types of travelers, advance formats, authorization procedures, communication between information systems, alternative booking channels, various sources of information, control and settlement of extra expenses, etc. The complexity of the travel account is also marked by the different types of travelers, advance formats, authorization procedures, communication between information systems, alternative booking channels, different sources of information, control and settlement of extra expenses, etc;The whitepaper published by Forum Business Travel, in collaboration with Notilus, shows the different information sources, alternative booking channels, control and settlement of extra expenses.