Can I give a company a report showing what each of its departments spent on travel?

Yes, and for most corporate clients this is the report they care about more than any other, because their finance team has to split travel cost across departments before they close their books. The usual way it works is that every booking carries a tag saying which department, cost centre or project the trip belongs to, and the report simply groups the bookings by that tag.

The important part is capturing the tag at the time of booking, not trying to work it out afterwards. So the traveller or the person booking for them is asked to pick a department from a list you have set up for that company, and the booking cannot be completed until they do. If you leave it as a free text box, you will get the same department typed in a different way each week and the report will never add up properly.

Be aware that the level of detail you can show depends on what the supplier sends back. The fare, the taxes and any charge you have added are normally there, so a department total is reliable. Splitting a single booking across more than one department, or reporting on something the supplier does not itemise separately, is harder and may not be possible for every supplier you sell through.

Before you set this up for a company, ask their finance team for the exact list of department or cost centre names they use in their own accounts, and load those same names in, so the report you hand over lines up with what they already have.