You can initiate bulk imports of clients, projects, tasks, or users if you go to the 'Account admin' tab:
Please select what to import and you will get detailed instructions on the screen. We strongly advise you to import your Projects and Clients first, and then proceed with Timesheets. This way the process will be completed much faster.
Please carefully follow the import format instructions on the screen, as it is really important how your data is formatted. The easiest way to get started is to download a prepared template which you can simply fill in.