If you examine the data directory of an older Tally company, you may find files with names such as:

• Company.900
• Manager.900
• TranMgr.900
• LinkMgr.900
• TranInf.900
• SumTran.900
• CfgRept.900

These files belong to an older generation of the Tally company-data architecture.

A common question for Tally users, IT administrators, data-recovery professionals and developers is:

What is the last version of Tally that uses .900 files?

The answer is:

TallyPrime Release 2.1 is the last TallyPrime release generation that uses the .900 company-data format.

Starting with TallyPrime Release 3.0, Tally introduced the newer .1800 data format. Tally's official data-migration documentation shows, for example, Company.900, Manager.900 and TranMgr.900 for TallyPrime 2.1, while TallyPrime 3.0 uses corresponding .1800 files.

Quick Answer

Tally generation	Typical data-file format
Older Tally 5.4 / 6.3 / 7.2	.500
Tally 9	.900
Tally.ERP 9	.900
TallyPrime 1.x	.900
TallyPrime 2.0	.900
TallyPrime 2.1	.900
TallyPrime 3.0	.1800
TallyPrime releases based on the newer architecture	.1800 generation

Therefore, if you specifically need a TallyPrime version capable of working with the old .900 company-data generation without first converting that company to the Release 3.0 format, TallyPrime Release 2.1 is the important cutoff point. Tally's current migration documentation explicitly distinguishes data from Release 2.1 or earlier from data belonging to Release 3.0 or later.

Understanding Tally Company Data Files

Tally does not normally store an entire company in one simple database file.

A company's data directory contains multiple files responsible for different parts of the company's accounting information and database operations.

For example, in a TallyPrime 2.1 company you may see files such as:

Company.900

Manager.900

TranMgr.900

LinkMgr.900

TranInf.900

SumTran.900

CfgRept.900

These files collectively form part of the company's Tally database.

Therefore, simply copying one .900 file usually does not constitute a complete company backup.

The safest practice is to back up the complete company using Tally's backup facility or preserve the complete company-data directory when performing technical troubleshooting.

What Does the .900 Extension Mean?

The .900 extension identifies files belonging to the older Tally database generation used across Tally 9, Tally.ERP 9 and earlier TallyPrime releases.

It should not be confused with an ordinary document extension such as:

.DOCX

.XLSX

.PDF

.CSV

A file such as Manager.900 is an internal Tally database component. It is not designed to be opened directly in Microsoft Excel, Notepad or another general-purpose database program.

The .900 suffix therefore tells an administrator something important about the generation of the Tally data structure.

Which TallyPrime Version Was the Last to Use .900?

The key transition occurred between:

TallyPrime Release 2.1 → TallyPrime Release 3.0

Tally's official documentation provides a useful comparison.

For company information, TallyPrime 2.1 uses files including:

Company.900
AddlCmp.900
CmpSave.900

TallyPrime 3.0 uses:

Company.1800
AddlCmp.1800
CmpSave.1800

For master information, Release 2.1 uses files including:

Manager.900
LinkMgr.900

Release 3.0 uses files including:

Manager.1800
ExtMngr.1800
LinkMgr.1800

For transactions, Release 2.1 uses:

TranMgr.900
TranInf.900

whereas Release 3.0 uses:

TranMgr.1800

Tally documents these structural differences in its official data-migration and data-corruption FAQ.

Important TallyPrime 2.1 .900 Files

1. Company.900

Company.900 contains company-level information.

This includes information related to the company's configuration and other company-specific settings.

It is one of the fundamental files associated with the company database.

2. Manager.900

Manager.900 is particularly important because it stores master-related information.

Examples of masters include:

• Ledgers
• Stock Items
• Stock Groups
• Accounting Groups
• Other company masters

Tally's troubleshooting documentation specifically refers to Manager.900/.1800 when diagnosing company-data problems.

3. TranMgr.900

TranMgr.900 is associated with transaction information.

This makes it one of the most important files when investigating missing or corrupted transaction data.

Tally's FAQ also identifies a specific condition in which Error Code 0 can occur when TranMgr.900 has an abnormal file size such as 1 KB.

4. LinkMgr.900

LinkMgr.900 is associated with linked information within the Tally database.

This can include relationships such as bill-wise details, order references and other linked master/transaction information.

5. TranInf.900

TallyPrime 2.1 also uses TranInf.900.

According to Tally's data-structure documentation, this file contains information related to transaction/voucher-numbering history.

6. SumTran.900

SumTran.900 is associated with summary or secondary transaction information in the Release 2.1 architecture.

In the Release 3.0 structure, Tally documents SecTran.1800 for corresponding secondary-transaction storage.

7. CfgRept.900

CfgRept.900 stores information relating to report configurations, including configurations created when report views are saved.

TallyPrime 3.0 uses CfgRept.1800 in the newer format.

What Changed in TallyPrime Release 3.0?

TallyPrime Release 3.0 represented a significant product and data-management transition.

Among other changes, Release 3.0 introduced features such as multiple GST registrations within a single company and improvements to GST configuration, reports, filters, payment functionality and data-management operations.

More importantly for this discussion, the underlying company-data structure moved from the .900 generation to the .1800 generation.

For example:

TallyPrime 2.1	TallyPrime 3.0
Company.900	Company.1800
AddlCmp.900	AddlCmp.1800
CmpSave.900	CmpSave.1800
Manager.900	Manager.1800
LinkMgr.900	LinkMgr.1800
TranMgr.900	TranMgr.1800
SumTran.900	SecTran.1800
CfgRept.900	CfgRept.1800

Release 3.0 also introduced additional database components such as ExtMngr.1800, Aggr.1800, VchStatus.1800 and StatStatus.1800.

How Can You Identify Whether Tally Data Is .900 or .1800?

If you have a Tally company-data folder but do not know which generation it belongs to, examining the files can provide a strong indication.

Example of older data

If the folder contains:

Company.900
Manager.900
TranMgr.900

you are looking at the .900 generation.

Example of newer data

If you find:

Company.1800
Manager.1800
TranMgr.1800

the company belongs to the newer Release 3.0-or-later data architecture.

This can be extremely useful when recovering old backups or identifying why a company is not opening in a particular Tally installation.

Five-Digit and Six-Digit Company Folders

There is another important clue.

When migrating company data from TallyPrime Release 2.1 or earlier to Release 3.0 or later, Tally migrates the existing company into a new company with a six-digit company number.

The original older company uses the previous five-digit company-number structure and is retained so that it can still be used with the previous compatible release.

For example, conceptually you might have:

Old company: five-digit company folder

and after migration:

Migrated company: six-digit company folder

This distinction can be very useful when an administrator finds both old and migrated company directories on a server.

Can TallyPrime 3.0 or Later Open .900 Data?

The important distinction is between opening data directly in its old format and migrating the data.

When older data from TallyPrime 2.1 or earlier is brought into Release 3.0 or later, Tally provides a migration process.

In TallyPrime, migration can be initiated through:

Alt+Y (Data) → Migrate

or, in current releases:

F1 (Help) → Troubleshooting → Migrate

depending on the workflow/version.

The old company is migrated into the newer company-data structure.

Does Migration Delete the Original .900 Company?

Normally, the migration process is designed to preserve the previous company.

Tally states that when migrating from Release 2.1 or earlier to Release 3.0 or later, the data is migrated from the existing five-digit company to a new six-digit company, while the original five-digit company is retained for use with the previous release.

Nevertheless, you should always take an independent backup before migration.

Do not depend exclusively on the migration process as your backup strategy.

Recommended Backup Procedure Before Migrating .900 Data

Before attempting migration, repair or experimentation with old Tally data:

1. Close TallyPrime on all computers accessing the company.
2. Ensure that no user is entering vouchers.
3. Take a normal Tally backup.
4. Make an additional copy of the complete data directory.
5. Store the second copy on another disk or backup location.
6. Do not experiment on your only available copy.
7. Verify the version from which the data originated, if possible.
8. Check that sufficient disk space is available.
9. If data appears corrupted, investigate or repair it before migration.
10. After migration, verify important accounting reports and transaction counts.

Current Tally documentation recommends taking a backup before migration, and newer migration processes can also perform pre-migration checks for exceptions or corruption.

Can TallyPrime 2.1 Open .1800 Files?

You should not expect TallyPrime 2.1 to work with a company that has already been converted to the Release 3.0 .1800 database architecture.

This is one reason why retaining the original .900 company before migration is important.

If you need access from TallyPrime 2.1, use the preserved pre-migration .900 company, rather than attempting to make Release 2.1 read the newer .1800 company.

Can You Convert .1800 Back to .900?

Tally's normal migration workflow is designed to move older data forward into a newer compatible format.

It should not be assumed that simply changing:

Manager.1800

to:

Manager.900

or changing other file extensions will convert the database.

Renaming the extension does not convert Tally data.

The internal database structure is different.

If older-version compatibility is required, the safest solution is to preserve and use the original pre-migration .900 company.

Never Manually Rename .900 to .1800

Do not attempt something like:

Manager.900 → Manager.1800

or:

TranMgr.900 → TranMgr.1800

Windows will allow you to rename a file extension, but this does not transform its internal database format.

Such manual manipulation may make troubleshooting more difficult and can potentially leave you without a usable copy if performed on the original data.

Always work on a backup copy.

Why Would Someone Still Need .900 Files?

There are several practical reasons.

1. Old Tally Installation

A business may still be operating Tally.ERP 9 or TallyPrime 2.1.

2. Historical Backup

An auditor or accountant may need to access a company backup from an older financial year.

3. Data Recovery

A damaged disk may contain an old Tally company folder with Manager.900 and TranMgr.900.

4. Third-Party Integration

Older Tally utilities or customized solutions may have been developed around an older Tally environment.

5. Forensic or Technical Analysis

An IT administrator may need to determine which Tally generation created a recovered company folder.

6. Migration

A company may need to migrate historical accounting data to a current TallyPrime release.

Important Warning for Third-Party Software Developers

Developers should be particularly careful about designing applications that depend directly on Tally's internal database files.

A utility designed around files such as:

Manager.900

TranMgr.900

LinkMgr.900

may not automatically work with:

Manager.1800

TranMgr.1800

LinkMgr.1800

The change is not necessarily just an extension change.

TallyPrime 3.0 introduced structural changes and additional database components.

Where possible, integrations should use supported Tally integration mechanisms rather than making assumptions about undocumented internal database structures.

What Is Manager.900 Corruption?

One symptom of damaged older Tally data can involve Manager.900.

Tally's official troubleshooting documentation states that a Memory Access Violation can occur when company data is corrupted and specifically recommends checking the size of Manager.900/.1800.

If the Manager file is only around 1 KB, Tally recommends restoring an earlier backup. If it is larger and the data still has problems, repair may be required.

This demonstrates why Manager.900 is an important diagnostic file when investigating old Tally company data.

What Is TranMgr.900 Error Code 0?

Tally's FAQ also documents Error Code 0 in relation to old data.

One documented cause is when:

TranMgr.900

has a file size of only 1 KB.

Because TranMgr.900 contains transaction-related data, abnormalities in this file should be treated seriously.

Do not repeatedly modify or repair your only copy of the company.

Create a backup first.

Migration from Tally.ERP 9 to Modern TallyPrime

Tally.ERP 9 data also belongs to the .900 generation.

Therefore, businesses moving from Tally.ERP 9 to modern TallyPrime may encounter the same data-generation transition.

For much older products such as Tally 5.4, 6.3 or 7.2, the process can involve an intermediate migration through Tally.ERP 9 before migration to TallyPrime. Tally's documentation specifically describes this migration path.

Migration Path at a Glance

A simplified historical migration path can therefore look like:

Older .500 generation

↓

Tally.ERP 9 / .900 generation

↓

TallyPrime 2.1 / .900 generation

↓

TallyPrime 3.0+ / .1800 generation

The exact procedure should always be selected according to the original Tally version and the destination release.

Post-Migration Verification

Successfully seeing a "Migration Successful" message should not be the end of the process.

After migration, verify critical information such as:

• Company name
• Financial years
• Ledgers
• Groups
• Stock items
• Opening balances
• Closing balances
• Day Book
• Sales vouchers
• Purchase vouchers
• Receipt vouchers
• Payment vouchers
• Journal vouchers
• Debit/Credit Notes
• Outstanding receivables
• Outstanding payables
• Stock summary
• GST configuration
• GST reports
• Voucher numbering
• Cost centres, where applicable
• Bank reconciliation information
• Edit Log information, where applicable

Tally also documents post-migration procedures for handling exceptions and validating migrated information.

Important Consideration for Edit Log Data

If the company uses Edit Log functionality, migration deserves additional attention.

Tally documents different outcomes depending on whether Edit Log was enabled in TallyPrime 2.1 and which Release 3.0-or-later product/version receives the migrated company.

Existing Edit Log information can be carried forward in supported migration scenarios.

Therefore, organizations subject to audit or compliance requirements should verify Edit Log information after migration rather than assuming that only accounting balances matter.

.900 vs .1800 – Technical Comparison

Feature	.900 generation	.1800 generation
Typical TallyPrime generation	Up to Release 2.1	Release 3.0 onward
Company file	Company.900	Company.1800
Master file	Manager.900	Manager.1800
Transaction file	TranMgr.900	TranMgr.1800
Link manager	LinkMgr.900	LinkMgr.1800
Report configuration	CfgRept.900	CfgRept.1800
Summary/secondary transactions	SumTran.900	SecTran.1800
Additional newer structures	Limited to older architecture	Includes additional Release 3.0 structures
Old company numbering during migration	Five-digit source company	New six-digit migrated company
Recommended action	Preserve before migration	Use with compatible newer release

Best Practices for Businesses Maintaining Old Tally Data

Organizations often retain accounting records for many years. It is therefore advisable to maintain old Tally data carefully.

A good archival strategy should include:

1. Keep multiple backups

Maintain more than one copy of important accounting data.

2. Record the originating Tally version

A text document accompanying the backup can mention:

• Tally version
• Release number
• Company name
• Company number
• Financial year
• Backup date

3. Preserve the original data

Do not migrate your only copy.

4. Keep migrated data separately

Maintain separate directories for old and newly migrated companies.

5. Test restoration periodically

A backup that cannot be restored is not a reliable backup.

6. Protect data from ransomware

Maintain at least one backup that is not permanently writable from the production computer/server.

Frequently Asked Questions (FAQ)

1. What is the last TallyPrime version that uses .900 files?

TallyPrime Release 2.1 is the last TallyPrime release generation using the .900 company-data format. TallyPrime Release 3.0 moved to .1800.

2. Does Tally.ERP 9 use .900 files?

Yes. Tally's documentation lists Tally 9/Tally.ERP 9 within the .900 data generation.

3. Does TallyPrime 1.x use .900 files?

Yes. Earlier TallyPrime releases prior to the Release 3.0 architecture use the older .900 generation.

4. Does TallyPrime 2.1 use Manager.900?

Yes. Tally's official comparison lists Manager.900 and LinkMgr.900 for TallyPrime 2.1.

5. Which version introduced .1800 files?

TallyPrime Release 3.0 introduced the .1800 company-data generation documented by Tally.

6. What is Manager.900?

It is an important Tally database file containing master-related accounting information such as ledgers, stock items and groups.

7. What is TranMgr.900?

It is a Tally database component associated with company transaction information.

8. Can I open Manager.900 directly?

It should not be treated as an ordinary standalone document. Access company information through a compatible Tally installation and the complete company-data set.

9. Can I open .900 data in a newer TallyPrime release?

Older Release 2.1-or-earlier data can be migrated to newer TallyPrime releases using Tally's migration process.

10. Will migration convert .900 data to .1800?

Migration from the Release 2.1-or-earlier architecture to Release 3.0-or-later creates the company in the newer data structure.

11. Can I rename .900 files to .1800?

No. Renaming the extension does not convert the internal database format.

12. Can TallyPrime 2.1 open a migrated .1800 company?

You should use the original preserved .900 company with the older compatible release rather than expecting Release 2.1 to read the newer Release 3.0 database structure.

13. Is the old company deleted after migration?

Tally states that when migrating Release 2.1-or-earlier data to Release 3.0 or later, the original five-digit company is retained while a new six-digit company is created.

14. Why do I see both five-digit and six-digit Tally company folders?

This can occur after migration. The older company uses the previous five-digit numbering, while migration to the Release 3.0-or-later architecture creates a six-digit company.

15. What happens if Manager.900 is only 1 KB?

Tally identifies this as a possible sign of data corruption and recommends restoring an earlier backup in the documented scenario.

16. Can TranMgr.900 cause Error Code 0?

Yes. Tally documents a case where Error Code 0 occurs when TranMgr.900 has a file size of 1 KB.

17. Should I back up data before migration?

Absolutely. A complete verified backup should be taken before migration, repair or other major data operations.

18. Can I continue using old data after migration?

The original company can be retained for use in the previous compatible release. However, avoid independently entering transactions into both old and migrated companies unless you have a deliberate reconciliation strategy.

19. Does TallyPrime 3.0 have the same database structure as 2.1?

No. Release 3.0 introduced the .1800 architecture and additional database components.

20. How do I know whether my Tally data is .900?

Open the company folder in Windows File Explorer. Files such as Company.900, Manager.900 and TranMgr.900 indicate the .900 generation.

21. How do I identify .1800 data?

Look for files such as Company.1800, Manager.1800 and TranMgr.1800.

22. Is .900 data necessarily corrupted because it is old?

No. .900 is a legitimate Tally data format. The extension itself does not indicate corruption.

23. Should I delete .900 files after upgrading Tally?

It is generally wise to preserve historical backups rather than immediately deleting the original data after migration.

24. Can third-party software designed for .900 files automatically work with .1800?

Not necessarily. Developers should verify compatibility because Release 3.0 introduced changes to the data architecture.

25. What is the safest approach when I discover old .900 Tally data?

First create a complete backup of the folder. Determine the Tally generation that created it, use a compatible Tally environment where appropriate, and perform migration only on a protected copy.

Conclusion

The most important technical point is simple:

TallyPrime Release 2.1 is the last TallyPrime release generation that uses the .900 data-file format. TallyPrime Release 3.0 introduced the newer .1800 data structure.

This distinction becomes especially important when working with old company backups, Tally.ERP 9 data, data-recovery cases, third-party integrations, legacy Tally installations and migrations to current TallyPrime releases.

If a company folder contains files such as:

Company.900
Manager.900
TranMgr.900

it belongs to the older .900 data generation.

If it contains:

Company.1800
Manager.1800
TranMgr.1800

it belongs to the newer .1800 generation introduced with TallyPrime Release 3.0.

Never attempt to convert these databases merely by renaming their file extensions. Always maintain a verified backup and use Tally's supported migration process when moving old accounting data to a newer release.

Official reference: TallyHelp – Data Migration and Data Corruption FAQ

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