At the end of the year, can I see which of my regular clients actually brought me the most business?

Yes, a report by client is one of the easier things to pull out of a booking system, because every booking is already tied to the customer or the company account that made it. You can normally set a date range, pick a year or a quarter, and get a list of your accounts ranked by the value of what they booked, along with how many bookings each one made and what they spent it on, whether that was flights, hotels, transfers or full packages.

This is worth doing once a year even if you think you already know the answer. Most agencies find that the client they spend the most time on is not the client that pays them the most, and seeing it written down in order changes how you plan your staff time and where you offer better terms. If you deal with corporate accounts, the same report usually lets you go one level deeper and see which departments or which travellers inside a company are generating the volume.

The honest limit is that the report can only count what went through the system. Bookings you made directly with a supplier and never entered, or business handled offline over the phone and never logged, will simply not appear, and the ranking will be wrong in a way that is hard to spot. How much history you can pull in one go can also depend on your plan.

Before you rely on the numbers, run the report for a month you remember well and check that the totals match what you actually did, so you know the picture is complete.