Using the regular time entries endpoint (https://api.track.toggl.com/api/v9/me/time_entries) you can get time entries from up to three months ago, including their IDs.
To get time entries from more than 3 months ago you have to use the reports endpoint instead e.g. detailed reports (https://api.track.toggl.com/reports/api/v3/workspace/{workspace_id}/search/time_entries.csv). However, this endpoint does not give you IDs for the time entries it returns, similiar to the CSV export from within the Toggl Track web app. Is there any way to get time entries with their IDs from 3+ months ago?
Hi @conormcleod 
Thanks for posting!
I’m afraid there’s no way to get time entry data older than three months, including time entry IDs, using the Reports endpoints. Sorry about that! I’ll share this with the team as a feature request, and if you don’t mind, I’ll move your post to the Product Feedback category