TLG is an extension that is unique to QuickBooks financial management software. TLG is a log file of activities that have been performed in a file with relevant program data with the QBW extension.

Such a file can be used to recover data in the event of a QBW file corruption, e.g. due to its improper closing or loss of the program's connection with the database. In such a case, transactions that have not been completed will be performed automatically after restarting the program and loading data from the TLG file.