Understanding QuickBooks Company Files and Their Companion Extensions
Learn what the .QBW, .TLG, .ND, .ADR and .QBB files do, which hold your live data, and how to keep them safe for recovery.
QuickBooks Desktop users often notice several files sharing the same name but with different extensions sitting beside the main company file. This cluster can raise questions about which file actually stores the accounting data, which are safe to delete, and which are essential for recovering information after a problem. Knowing the purpose of each companion file helps prevent accidental loss and clarifies what a recovery process relies on when the primary file won’t open.
What the .QBW File Is
The file with a .QBW extension is the live QuickBooks company file. It contains all of the transactional data, lists, preferences, and reports that you work with daily. When you open QuickBooks Desktop and load a company, the program reads this file to display your books. No other file holds the current, editable data; the .QBW is the sole source of truth for your accounting records while the program is running.
Role of the .TLG Transaction Log
Alongside the .QBW, QuickBooks maintains a transaction log with a .TLG extension. This log records every change made to the company file since the last backup was taken. If a backup is restored, the .TLG can replay the transactions that occurred after that backup point, bringing the file up to a more recent state. Because of this function, the .TLG should not be deleted casually; it forms part of the safety net that enables recovery of recent work when a backup is used.
Understanding .ND and .ADR Files
The .ND file is a small network‑data configuration piece. It tells workstations how to locate the company file when QuickBooks runs in multi‑user mode. The .ND does not store any accounting information; if it becomes corrupted, QuickBooks can recreate it, a task often handled by the Database Server Manager or the File Doctor utility.
Auto Data Recovery files appear with an .ADR extension. QuickBooks periodically creates copies of both the company file and its transaction log and stores them in an Auto Data Recovery folder. These copies are typically only a few hours old. If the working .QBW becomes damaged, the program can attempt to restore data from the most recent .ADR pair, providing a recent fallback without needing to rely on a manual backup.
Backup and Portable Files (.QBB and .QBM)
When you choose File > Back Up Company, QuickBooks produces a .QBB file. This is a complete backup of the company file at the moment the backup runs. Restoring a .QBB creates a new .QBW that matches the state of the data when the backup was taken. A .QBM file, by contrast, is a compressed portable copy designed for moving a company file between computers or sending it to an accountant. Neither the .QBB nor the .QBM is the active file; they serve as restore points or transfer mechanisms.
Best Practices for Keeping Companions Safe
For everyday protection, schedule regular backups to generate fresh .QBB files and retain the corresponding .TLG alongside the primary .QBW. Avoid manually deleting any of the companion files unless you are certain they are obsolete—such as old .ND files after a network reconfiguration or outdated .ADR copies that QuickBooks has already purged. If a .QBW refuses to open, the recovery process typically combines the damaged .QBW with its most recent .TLG and any available Auto Data Recovery copies to rebuild the data as completely as possible.
By recognizing that the .QBW holds the live data while the .TLG, .ND, .ADR, .QBB, and .QBM files play supporting roles in networking, recovery, backup, and portability, users can make informed decisions about file management. Keeping these companions intact and backed up reduces the risk of data loss and simplifies troubleshooting when QuickBooks Desktop encounters issues.