File Extension Guide📖 What is a Tally Data File?
A Tally data file is one of the files that the accounting software uses to store a company. No single file holds the whole company. Masters go into one file, vouchers into another and company settings into a third. The software reads them together when you select the company.
Tally Solutions changed the data format three times, and each change brought a new extension. Tally 5.4, 6.3 and 7.2 wrote .500 files. Tally 9, Tally.ERP 9 and the first TallyPrime releases up to 2.1 wrote .900 files. TallyPrime Release 3.0 introduced the .1800 format, and every later release uses it.
The one rule to remember
Copy the whole company folder before you repair, migrate or move it. A single .900 or .1800 file is useless on its own, and the repair screen itself offers a backup first.
🔎 Which Tally File Do I Have?
The extension and the folder name answer it in most cases. Find the card that fits your file.
.1800 files
TallyPrime Release 3.0 and later. The company folder has a 6-digit number.
100000\Company.1800, Manager.1800, TranMgr.1800.900 files
Tally 9, Tally.ERP 9 and TallyPrime Release 1.0 to 2.1. The company folder has a 5-digit number.
10000\Company.900, Manager.900, TranMgr.900.500 files
Tally 5.4, 6.3 and 7.2. Besides Company.500 and Manager.500, the folder holds numbered files such as Tr01263.500.
Company.500, Manager.500, Tr01263.500.001 backup files
A company backup made with the Backup option. Tally.ERP 9 names it TBK900.001 and TallyPrime 3.0 to 6.2 name it TBK1800_ plus the company number.
TBK900.001, TBK1800_100000.001.TSF files
Temporary files kept beside the data. The ledgers and vouchers live in the .900 or .1800 files.
TSTATE.TSF, TMESSAGE.TSF, TACCESS.TSFSome files now end in 1800
Tally says this means the data was opened in a higher TallyPrime release. An older release will no longer open it.
Company.1800 where Company.900 used to be🗂️ What is Inside a Tally Company Folder?
The official data migration FAQ lists each file and its job. A TallyPrime 3.0 or later company folder holds these files. A .900 folder has the same core names with the older extension.
| File | What it stores |
|---|---|
Company.1800, CmpSave.1800, AddlCmp.1800 | Company information, security control and F11 features |
Manager.1800 | All masters, such as ledgers, groups and stock items |
ExtMngr.1800 | Edit Log information and data that helps Tally recompute dependencies |
LinkMgr.1800 | Master link information |
TranMgr.1800 | Transactions (vouchers) |
SecTran.1800 | Summary transactions |
CfgRept.1800 | Report configurations |
Aggr.1800 | Precalculated aggregate values |
VchStatus.1800, StatStatus.1800 | Voucher status and statutory status |
TSTATE.TSF, TMESSAGE.TSF, TACCESS.TSF, TUPDATE.TSF | Temporary files used while Tally runs |
Three files matter most when something goes wrong. Manager holds the masters, TranMgr holds the vouchers and Company holds the company details. Several damage errors in the official help pages name one of these three files.
🔢 Why Do Tally Company Folders Have 5 or 6 Digits?
The folder name is the company number. Tally.ERP 9 and TallyPrime up to 2.1 use 5-digit numbers. When TallyPrime Release 3.0 migrates a company, it creates a new company with a 6-digit number, such as 100000. Tally says the 6-digit number is there "to break the compatibility of that data in the earlier TallyPrime release".
Data path
├── 10000 # original 5-digit company, .900 files
└── 100000 # migrated 6-digit company, .1800 files
The original 5-digit company stays in place, so the previous release can still use it. Expect the migrated folder to be larger. The help page explains that migration adds internal "purpose data" for faster GST and Edit Log reports. Migration only goes forward: data moved into TallyPrime does not load in Tally.ERP 9 again.
💾 What Do Tally Backup Files Look Like?
A Tally backup is a separate file with the .001 extension. The name changes with the release:
| Backup file name | Made by |
|---|---|
TBK900.001 | Tally.ERP 9 Release 6.x |
TBK1800_<company number>.001 | TallyPrime Release 3.0 to 6.2 |
TDBK1800_<company number>.001 | TallyPrime Release 7.0 and later, one-time backup |
TSDBK1800_<company number>.001 | TallyPrime Release 7.0 and later, scheduled backup |
Tally opens a backup only after a restore. In TallyPrime, use Alt+Y (Data) > Restore. In Tally.ERP 9, use Gateway of Tally > F3: Cmp Info > Restore. Tally's FAQ also states that a tbk.900 backup recovered with a third-party recovery tool cannot be restored.
⚠️ Which Errors Mean a Tally Data File is Damaged?
Each message below comes from the official help pages. Each one points to a damaged or mismatched data file.
| Message | Cause given by Tally |
|---|---|
| Error Code 0 | TranMgr.900 or TranMgr.1800 is only 1 KB in size |
| Memory Access Violation | Damaged data such as a 1 KB Manager file. A TDL add-on can cause it too |
| File Damaged or Repair Required | The company data is damaged. Tally asks you to upgrade and repair |
| Data files damaged. Need to rewrite. | Tally.ERP 9 asks for a rewrite of damaged data |
| Error Tranmgr.1800, Linkmgr.1800 or Manager.1800 | One of the core data files is damaged |
| Unable to open the company in this release of TallyPrime | The data was saved by a higher TallyPrime release |
| Unable to Read Message for Update | The TMESSAGE.TSF file is damaged |
Tally's fix for most of them is a repair: Alt+Y (Data) > Repair or Ctrl+Alt+R in TallyPrime. Say Yes when it offers to back up the company first. The help pages also warn that data can be damaged inside with no status shown, so a company that opens is not proof of healthy files.
📂 How Do You Open a Tally Data File?
The right method depends on what you have and what is installed on the computer.
- With TallyPrime installed. Press Alt+Y (Data) > Data Path and point it at the folder that holds the company folder. Then select the company with Alt+F3. In TallyPrime 3.0 or later, a .900 company opens after migration.
- With a backup only. Restore the .001 file through the Restore option, then select the restored company.
- Without Tally. Univik Tally Data Viewer reads .500, .900 and .1800 company folders and .001 backups without Tally installed. It opens the data read-only, so the files stay unchanged.
To move the data into other programs, Univik Tally Data Converter saves Tally data as CSV, Excel, XML, JSON, PDF, TXT, HTML or SQL. For audits and investigations, Univik Tally Data Forensic Analyzer reads the evidence read-only and adds hash values to its report.
TallyPrime's own Export option (Alt+E) also saves reports as Excel, PDF, XML, JSON, HTML, JPEG or ASCII text, but it needs the software running with the company open.
⚔️ How Do Tally File Formats Compare?
| Extension | Written by | Core files | Path to current TallyPrime |
|---|---|---|---|
| .500 | Tally 5.4, 6.3, 7.2 | Company.500, Manager.500, Tr*.500 | Move to Tally.ERP 9 with tally72migration.exe, then migrate in TallyPrime |
| .900 | Tally 9, Tally.ERP 9, TallyPrime 1.0 to 2.1 | Company.900, Manager.900, TranMgr.900 | Migrate in TallyPrime 3.0 or later |
| .1800 | TallyPrime 3.0 and later | Company.1800, Manager.1800, TranMgr.1800 | Opens in TallyPrime 3.0 or later |
Data from Tally 5.4, 6.3 or 7.2 cannot go straight to TallyPrime. Tally's migration guide moves it to Tally.ERP 9 first.
❓ Tally Data File Questions
A .900 file is a Tally data file written by Tally 9, Tally.ERP 9 or TallyPrime Release 1.0 to 2.1. Each company folder holds several of them, such as Company.900, Manager.900 and TranMgr.900. Only Tally or a dedicated data reader can open them.
A .1800 file is a Tally data file written by TallyPrime Release 3.0 or later. Release 3.0 brought a new data format, so Company.1800, Manager.1800 and TranMgr.1800 take the place of the .900 files after migration. A company with .1800 files does not open in an older TallyPrime release.
TranMgr.900 is the file that stores the vouchers of a Tally company. In TallyPrime 3.0 and later it is called TranMgr.1800. Tally shows Error Code 0 when this file is only 1 KB in size.
TSF files such as TSTATE.TSF, TMESSAGE.TSF and TACCESS.TSF are temporary files that Tally keeps beside the data files. The accounting data itself sits in the .900 or .1800 files. The official advanced repair steps remove some TSF files, so work on a copy with Tally closed if you follow them.
TallyPrime Release 3.0 gives each migrated company a new 6-digit number, such as 100000, to break compatibility with earlier releases. The original 5-digit company stays in place for use in the previous release.
TBK900.001 is a Tally.ERP 9 backup. Tally opens it only after a restore through Gateway of Tally > F3: Cmp Info > Restore. Univik Tally Data Viewer reads the backup file directly, with no restore step.
No. Tally shows the message Unable to open the company in this release of TallyPrime when data from a higher release is loaded in a lower one. Open the company in TallyPrime 3.0 or later, or read it with a Tally data reader.
In the company data path set in Tally. In TallyPrime, press Alt+Y (Data) > Data Path to see or change it. Each company sits in its own numbered folder inside that path.
📝 Tally Data Files in Summary
- .1800 files come from TallyPrime 3.0 and later
- .900 files come from Tally.ERP 9 and TallyPrime up to 2.1
- .500 files come from Tally 5.4, 6.3 and 7.2
- TranMgr stores vouchers and Manager stores masters
- A 6-digit folder is a company migrated to 3.0
- Backups end in .001 and need a restore first
- Error Code 0 means a 1 KB TranMgr file
- Copy the whole folder before any repair
Last updated 5 October 2026. Every fact here is sourced to Tally Solutions' own help pages, with a link where it first appears.