GST Data Cleanup Checklist Before Software Migration

Why Data Cleanup Must Come Before Migration

A migration utility can move records from one system to another. It cannot always determine whether those records are correct.

A GSTIN may follow the required format but belong to the wrong branch. An HSN code may be valid but unsuitable for the item. A purchase register may contain credits that appear in the books but are reversed, blocked or still under review for GST purposes. Effective GST data hygiene therefore involves three separate stages:

These stages should happen in this order. Mapping unclean data only transfers the same problems into a different system.

1. Define the Migration Scope and Cut-off

Begin by deciding exactly what the business needs in the new system. Importing every available record is not always the safest option. Older closed periods may be kept in an accessible archive, while the live migration may include:

• Party, item and ledger masters
• Opening receivables and payables
• Opening stock quantities and values
• Bank and cash balances
• Current-year transactions
• Outstanding orders, challans and advances
• Open GST documents
• Historical records required for reporting or audit

The cut-off plan should clearly record the last entry date in the old software and the first entry date in the new one. It should also explain how backdated invoices, late purchase documents and corrections received after the cut-off will be handled.

A financial-year start can simplify the process, but it is not compulsory. A mid-year migration can work when invoice numbering, return periods, opening balances and late documents are controlled properly.

Cut-off decisions to record

2. Create Backups and Capture the Baseline

Create one complete backup before correcting the source data and another immediately before the final import. Do not assume that copying the database folder is enough. Test whether the backup can be restored and opened with the required software, credentials, and database version. The pre-migration baseline should include:

These reports establish what was present before migration. Without them, the team may not be able to determine whether a difference existed in the old system or was introduced during import.

3. Complete GST Master Cleanup

GST master cleanup is one of the most important parts of the process because one incorrect master can affect hundreds of future transactions.

Verify Customer and Supplier Masters

For every active registered party, review the GSTIN, legal name, trade name, registration status, State of registration, and business address. A format check is not enough. A GSTIN can be technically valid but belong to another branch or legal entity. Also keep the following fields separate:

• Registration State
• Billing address
• Delivery address
• Place of supply

The State code in the GSTIN identifies the State of registration. It does not automatically determine the place of supply . Place of supply depends on the nature and circumstances of the transaction under the applicable IGST provisions.

Handle Duplicate Parties Carefully

Possible duplicates can be identified through the GSTIN, PAN, legal name, address, bank account, or contact details. However, two ledgers should not be merged merely because they have the same legal name or PAN. Different branches may have separate GST registrations and separate tax records. Before merging a genuine duplicate:

1. Select the master that will remain active.
2. Review both outstanding balances.
3. Transfer invoice and payment references.
4. Record the old and new master codes.
5. Preserve a merge log for future review.

Duplicate internal ledgers do not change the government-generated GSTR-2B. They do, however, make party reconciliation and invoice matching more difficult.

Review HSN, SAC and Units

Each active goods master should carry the appropriate HSN and each service master should carry the relevant SAC where required. Notification No. 78/2020-Central Tax prescribes the applicable HSN digit requirements on tax invoices. Broadly:

Do not create a code by shortening a longer HSN or adding digits to a shorter one. Select a valid classification from the official HSN master because changing the digits may change the classification itself.

Units should also be standardised. The same item should not appear under several variations such as “PCS”, “Piece”, “Nos” and “Units”. Map each item to the appropriate Unit Quantity Code used in GST reporting.

The GST portal’s GSTR-1 guidance requires separate B2B and B2C HSN summaries in Table 12 from May 2025.

Review GST Rates by Item and Effective Date

The GST rate changes effective from 22 September 2025 require businesses to review older tax masters. However, this does not mean that every 12% or 28% rate should be replaced automatically.

The revised rate schedules were introduced through Notification No. 9/2025-Integrated Tax (Rate), effective from 22 September 2025, and were subsequently amended by Notification No. 01/2026-Integrated Tax (Rate), dated 30 April 2026. The schedules include principal rates as well as special-rate entries, including a 28% schedule for specified goods. Check the current entry before changing an item master.

Historical vouchers must retain the rate that applied on their original transaction date. Updating the current item master should not rewrite completed transactions.

Rationalise Ledgers Without Losing History

Dormant zero-balance ledgers can be archived if they are no longer required. A ledger carrying an outstanding balance, dispute, or supporting document should remain available until its treatment is resolved.

When restructuring the chart of accounts, preserve a mapping between the old and new ledger codes. This is especially important for:

• Tax ledgers
• Freight and discount ledgers
• Round-off accounts
• Suspense accounts
• Expense ledgers
• Reverse-charge transactions

Reverse charge should be reviewed against the exact nature of supply, supplier category, recipient category, and applicable notification. It should not be applied through a broad supplier label alone.

4. Reconcile Transactions and Tax Balances

Keep ITC Records Separate

Book ITC, GSTR-2B, GSTR-3B, and the electronic credit ledger are related, but they are not the same record.

Differences may arise because of utilisation, timing, reversals, blocked credits , imports or documents still under review. Prepare a reconciliation schedule that explains each difference. Do not force all four records to one number through an unsupported opening journal.

Clean Receivables, Payables and Bank Entries

Before transferring outstanding balances, review:

• Receipts or payments adjusted against the wrong invoice
• Old advances
• Unallocated credit notes
• Negative party balances
• Duplicate vouchers
• Unidentified bank receipts
• Long-standing reconciliation differences
• Suspense balances

Every unresolved amount carried into the new system should have a clear narration, responsible owner, and expected resolution date.

Reconcile Inventory Properly

Compare the stock quantity and value in the source system with the available physical and operational records. The review may include:

• Godown-wise stock
• Batch and expiry details
• Serial numbers
• Goods sent for job work
• Goods moved through delivery challan
• Damaged or obsolete inventory
• Unit conversions
• Valuation method

A difference should not be cleared through a balancing stock journal until its cause is understood. The issue may lie in quantity, valuation, batch data, unit mapping, or a missing voucher.

Review Open GST Documents

Prepare an exception register for documents that remain unresolved at cut-off, such as:

• Unreported invoices
• Pending credit or debit notes
• Advances awaiting adjustment
• Open e-way bills
• Goods in transit
• Export documents
• Reverse-charge liabilities
• Amended invoices
• Documents awaiting IRN generation

The register should show the document number, value, tax effect, current status and responsible owner.

5. Protect Invoice and E-Invoice Continuity

Record the last number used in every invoice, credit-note and debit-note series before migration. Rule 46 allows one or multiple invoice series. The number must be consecutive within the selected series, unique for the financial year, and no longer than 16 characters.

A business does not have to restart every series at number 1 at the beginning of the financial year. It may continue the existing series if the numbering remains unique and compliant.

Invoice-series control table

E-invoicing generally applies to the notified class of taxpayers whose aggregate annual turnover exceeded ₹5 crore in any financial year from 2017-18 onwards, subject to notified exclusions.

For taxpayers with AATO of ₹10 crore or more, covered invoices, credit notes and debit notes must be reported to the IRP within 30 days of the document date from 1 April 2025. Any eligible document approaching this limit should be reported before migration work causes further delay.

6. Run a Controlled Test Migration

Do not test the migration using only a few simple vouchers. Select a small but representative sample that covers the main transaction types and GST treatments used by the business.

Choose records with different tax rates, document dates and party types. Also include at least one previously corrected or amended transaction, as these often reveal mapping problems that standard vouchers do not. After the test import, compare the old and new systems using the following reports:

Keep the old system as the official production record while the test is being reviewed. Unrestricted live posting in both systems can create duplicate records and make it unclear which data is final.

7. Complete the Final Pre-Migration Sign-off

Use this data migration checklist after completing the cleanup and test import.

Record Retention After Migration

Section 36 of the CGST Act generally requires records to be retained for 72 months from the due date of the annual return for the relevant financial year. Where an appeal, revision, proceeding or investigation is involved, the relevant records must be retained for one year after final disposal or for the normal 72-month period, whichever is later.

The law requires the records to remain accessible. It does not specifically require the business to maintain an active subscription to the old software. Test the archive before closing access to the old system. A practical archive should include:

• Native software backups
• Trial balances and detailed ledgers
• Invoice and voucher exports
• Stock reports
• GST return workings
• GSTR-1 and GSTR-3B copies
• Master-data exports
• E-invoice and e-way bill references
• Supporting documents
• Instructions needed to restore or read the backup

Where BUSY Fits Into the Migration Workflow

BUSY provides migration guides and utilities for businesses moving from Tally, Marg, Vyapar, Zoho and myBillBook. More than 6,00,000 businesses use BUSY for accounting, billing, inventory and GST compliance.

The Tally2BUSY utility can transfer master data such as ledgers, groups and items, along with sales, purchase and journal vouchers. BUSY’s migration guidance also recommends creating a backup, testing a smaller dataset, mapping account groups and verifying the imported data.

The migration utility can reduce the manual work involved in transferring records, but the business must still approve classifications, balances and unresolved exceptions. Clean the source data, test the import and obtain sign-off before switching to the new system.

Conclusion

A reliable migration begins with clean and explainable source data. Validate party and item masters, preserve historical tax treatment, reconcile GST balances separately and test the new system before go-live.

A properly completed data migration checklist should produce three clear outcomes: matching control totals, an approved exception register and an accessible audit trail. That is the purpose of GST data hygiene. It prevents the new system from beginning with errors inherited from the old one.