QuickBooks Desktop 2017 Company File Types and What to Back Up

Last reviewed 2026-07-05 4 min read

Understand QuickBooks Desktop 2017 file types (.QBW, .QBB, .QBM, .ND, .TLG) and learn exactly which files you must protect to keep your accounting data saf

If you are continuing to run QuickBooks Desktop 2017 after its May 31, 2020 discontinuation date, safeguarding your data is entirely in your hands. QuickBooks generates several different files when you create and operate a company, and knowing what each one does is critical to ensuring your financial history remains intact and accessible for the long haul.

The Primary Company File (.QBW)

The .QBW file is the master file. It contains all your financial data, transactions, lists, templates, and preferences. This is the file QuickBooks opens directly when you launch the program and select your company. Because it is the central hub of your data, the .QBW file is highly susceptible to corruption from sudden power losses, network hiccups, or improper system shutdowns. You must protect this file, but because it is prone to corruption, you should never rely on it as your sole backup.

The Backup File (.QBB)

The .QBB file is a compressed archive of your .QBW file. When you use the built-in backup utility in QuickBooks 2017, this is the file format the software creates. This is the most important file for your long-term survival on Desktop. If your live .QBW file ever fails to open or throws a fatal error, a recent .QBB backup is usually the fastest way to get back up and running. You should set QuickBooks to create .QBB backups automatically, and you should manually copy these .QBB files to an external drive or secure offline location regularly.

The Portable Company File (.QBM)

A .QBM is a highly compressed version of your company file designed specifically for easy transfer—usually via email or a cloud upload. It is significantly smaller than a standard .QBB backup. While incredibly useful for sending your data to an accountant or moving it between a desktop and a laptop, a .QBM is not a substitute for a full backup. It lacks some of the background data and attachment files found in a full backup. Use it for transit, but rely on .QBB files for safekeeping.

Supporting Configuration Files (.ND and .TLG)

QuickBooks 2017 generates auxiliary files in the same folder as your .QBW file. These support multi-user access and data recovery, and while they do not contain your primary accounting data, they are essential for the software to function smoothly.

The Network Data (.ND) file: This configuration file allows QuickBooks 2017 to access the company file in multi-user mode. If this file is missing or damaged, QuickBooks may fail to open the company file or default to single-user mode. Deleting a corrupted .ND file and opening the company file again forces QuickBooks to automatically rebuild a fresh one—a troubleshooting step that is identical across nearly all QuickBooks Desktop versions.
The Transaction Log (.TLG) file: This file records every single transaction entered into your company file since your last full backup. If your .QBW file is damaged, QuickBooks uses the .TLG file alongside your most recent .QBB backup to restore all data up to the exact minute the file failed. Never delete your .TLG file unless you have a completely current backup, as doing so will permanently sever your ability to recover recent transactions.

Which Files to Protect for the Long Haul

To keep your QuickBooks 2017 environment secure without relying on Intuit's discontinued services, prioritize your files in this order:

Always protect your .QBB backups. Store copies on external media disconnected from your main computer to protect against ransomware and hard drive failures.
Preserve your .QBW and .TLG files together. If you ever need professional data recovery, having both of these files exactly as they were at the time of failure gives you the highest chance of a full restoration.
Keep your .QBM files organized. Maintain a dedicated folder for any portable files you create, clearly dating them so you know exactly what data they contain.

If your primary .QBW file begins throwing C-series errors, fails to verify, or refuses to open entirely, stop entering data immediately. Attempt the built-in Verify and Rebuild utilities, and if those fail, rely on your .QBB backup. For deeply corrupted files that backups cannot solve, professional QuickBooks file repair services can often rebuild the damaged database structure directly, allowing you to stay on your 2017 software without losing your historical data.