Toggl to QuickBooks Integration works by periodically transmitting billable Toggl time entries to QuickBooks Online. Information that the time entry carries with it, such as duration, start and end times, description, hourly rate, and client information are used to create a corresponding time activity entry in QuickBooks Online. 

Toggl to QuickBooks Integration will periodically check for completed, billable time entries in Toggl (~30 minutes). Only time entries that are billable AND associated with a client (i.e a project) can be transferred to QuickBooks. 

The reason for this is that QuickBooks requires that time activities be associated with either a vendor or an employee. The Toggl to QuickBooks Integration uses the client name to determine which vendor or employee the activity is associated with.

After creating the time activities in QuickBooks, Toggl to QuickBooks Integration will then return to Toggl and tag the entries to mark them as synced.

Occasionally, there can be errors creating time activities in QuickBooks. Most errors are due to a billable client time entry in Toggl not matching up against an existing vendor or employee (the names must match exactly). You'll get a notification in your email with the error message. However, because you will need a chance to make corrections to resolve the error, the Integration tags the time entries so that they are not sent again until the issue has been resolved.

Once you have resolved the issue, simply remove the "SyncError" tags from your Toggl time entries, and Toggl to QuickBooks Integration will pick them up the next time it runs.