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ERP Data Migration Services: Scope, Timeline & Cost for Indian Businesses (2026)
Quick Answer: erp data migration services india cover the end-to-end extraction, transformation, and loading of financial, inventory, and statutory data from legacy ERPs (like SAP, Oracle, or custom builds) into target systems such as TallyPrime or cloud ERPs. A typical engagement includes chart-of-accounts remapping, opening-balance reconciliation, GST/TDS history migration, a parallel-run validation period, and formal cutover sign-off. Projects are fixed-fee quoted after a paid discovery phase; timelines range from 6–14 weeks depending on entity count, ledger volume, and statutory depth.
What Does ERP Data Migration Scope Actually Cover?
When a manufacturing group or trading conglomerate engages for migration, the scope is rarely "just data entry." It is a structured finance-IT project. The standard scope TACHY delivers includes:
- Discovery & Data Profiling: Source-system audit (SAP ECC/S4, legacy FoxPro, custom .NET, Excel dumps), row-count validation, and identification of dormant vs. active masters.
- Chart-of-Accounts (CoA) Remapping: Aligning source GL codes, cost centres, profit centres, and segments to the target CoA structure — often a many-to-one rationalization.
- Master Data Migration: Customers, vendors, items, units of measure, tax groups (GST HSN/SAC, TDS sections), and payroll heads.
- Transactional History Migration: Open invoices (AR/AP), stock on hand, WIP, fixed asset registers, and statutory history (GSTR-1/3B, TDS returns, TCS, e-invoice IRNs) for the agreed look-back period.
- Opening Balance Reconciliation: Trial balance match to the rupee at legal-entity level, including rounding-difference clearing accounts.
- Parallel Run & UAT: Side-by-side booking in old and new systems for 1–2 monthly cycles (or quarter-end) with variance logs.
- Cutover & Go-Live Support: Final delta load, user training, and 30-day post-go-live stabilization.
Out of scope unless explicitly added: custom Z-report recreation, third-party bolt-on integration (e.g., shop-floor MES, bank EBICS), and historical audit-log migration.
How long does a SAP to Tally migration take?
A SAP to Tally migration for a mid-market Indian manufacturing group (3–5 legal entities, 5–7 years of statutory history, ~15k active ledgers) typically runs 8–12 weeks from discovery sign-off to cutover.
| Phase |
Typical Effort (Weeks) |
Key Deliverable |
| Discovery & Profiling |
1–2 |
Data dictionary, gap register, migration spec sign-off |
| CoA Mapping & Build |
2–3 |
Mapping workbook, Tally company/ledger creation scripts |
| Extraction & Transformation |
2–3 |
Cleansed CSV/XML loads, tax-code cross-walk |
| Load & Reconciliation |
2–3 |
TB match certificate, GST register tally |
| Parallel Run (1–2 periods) |
2–4 |
Variance log < 0.1% net value |
| Cutover & Hypercare |
1–2 |
Delta load, go-live sign-off, 30-day support log |
Complexity multipliers: carve-out entities, multi-currency consolidation, inter-company elimination logic, and inventory batch/serial history depth.
What usually goes wrong? (Risk Register)
Implementation consultants see the same failure patterns repeatedly. Budget for these risks in your internal plan:
- Unmapped Ledgers / Orphan Codes: Source GLs with no target home — usually old project codes or one-time vendor accounts. Fix: Mandatory "Unmapped" clearing ledger in target with monthly review.
- GST/TDS Tax-Code Mismatches: SAP tax procedure codes (MWST, condition types) do not map 1:1 to Tally tax groups. HSN changes mid-year, composition vs. regular dealer shifts, SEZ/export flag gaps. Fix: Tax-code cross-walk validated against filed GSTR-1 JSONs, not just master data.
- Rounding Differences in Trial Balance: SAP allows 3-decimal currency; Tally forces 2. Cumulative rounding on high-volume AR/AP creates ₹1–₹5k variances per entity per month. Fix: Automated rounding-difference ledger posting rule defined before first load.
- Inventory Valuation Drift: Moving average vs. FIFO vs. Standard cost method mismatch; negative stock entries in source blocked in target. Fix: Valuation method alignment workshop; negative-stock cleanup script pre-migration.
- Statutory History Gaps: Carrying forward only open invoices loses the audit trail for filed returns. Fix: Migrate GSTR-1/3B JSON payloads and TDS FVU files as reference attachments in Tally (or document repository) even if not "live" for transacting.
- User Resistance During Parallel Run: Finance team books in old system only, treating new system as "test." Fix: Mandatory dual-entry policy with management sign-off on variance log weekly.
Buyer’s Readiness Checklist (share with your internal team before kickoff):
- [ ] Finalized target Chart of Accounts signed off by CFO/Statutory Auditor
- [ ] Legal entity list with CIN, GSTIN, PAN, TAN confirmed
- [ ] Decision on history depth: Current FY only vs. 3 FY vs. 7 FY (statutory minimum)
- [ ] Inventory valuation method locked (FIFO / Weighted Avg / Standard)
- [ ] List of custom Z-reports / MIS views required Day-1 vs. Phase-2
- [ ] IT infra ready: TallyPrime Server / Tally on Cloud credentials, backup policy
- [ ] Key users identified for UAT (2 per entity minimum)
- [ ] Cutover window frozen (e.g., quarter-end weekend) with board approval
Cost Drivers: Why Fixed Fee After Discovery?
TACHY quotes erp data migration services india as a fixed project fee only after a paid discovery engagement. The final number moves on these levers — not on headcount or day rates:
- Number of Legal Entities: Each CIN requires separate company creation, CoA, statutory registers, and TB sign-off.
- Active Ledgers & Cost Centres: 5,000 vs. 50,000 ledgers changes mapping effort exponentially (many-to-one logic, duplicate cleanup).
- Years of History Carried: Current FY + opening balances is baseline. Each prior FY adds extraction, GST reconciliation, and TB validation cycles.
- Statutory History Depth: Migrating GSTR-1/3B JSONs, TDS FVUs, e-invoice IRNs, and Form 26AS reconciliation data is effort-heavy but audit-critical.
- Custom Z-Reports / MIS: Rebuilding SAP ALV/ABAP reports in Tally TDL or Power BI is a separate workstream.
- Inventory Complexity: Batch/serial tracking, multi-godown, job-work ( challan), alternate units, expiry management — each adds mapping rows and validation scripts.
- Source System Hygiene: Clean SAP with archived documents migrates 40% faster than a 15-year-old custom ERP with hard-coded logic and no referential integrity.
The discovery phase (typically 1–2 weeks) produces the Migration Specification Document — the single source of truth for scope, exclusions, acceptance criteria, and the fixed fee. No surprises later.
How do we handle GST and TDS history during migration?
Statutory continuity is non-negotiable for Indian businesses. The migration must preserve the evidence of filed returns, not just the ledger balances.
- GST: We migrate the GSTR-1 (B2B, B2C, CDNR, EXP) and GSTR-3B summary data as reference tables/attachments in the target system. HSN-wise summary, document-level IRN mapping, and e-way bill linkage are validated against the GSTN portal before cutover. Input Tax Credit (ITC) carry-forward balances are posted to the correct electronic credit ledger heads.
- TDS/TCS: Section-wise (194C, 194J, 194Q, 206C(1H), etc.) challan-wise data is reconciled to Form 26AS / 27Q / 26QB filed returns. The TDS receivable ledger in Tally must match the Traces portal balance to the rupee on Day-1.
- Tally Specifics: TallyPrime’s statutory masters (GST rates, TDS sections) are pre-configured via TDL/import templates during the build phase so that the first voucher entry in the new system is already compliant.
FAQ
### Can we migrate only open items and current FY to save time?
Yes, many groups choose "Current FY + Opening Balances" as the minimum viable scope. However, auditors and tax authorities expect access to prior-year GST/TDS records. If you truncate history, you must retain read-only access to the source system (SAP archive server or static backup) for at least 8 years under Section 44AA/Rule 6DD. TACHY can build a lightweight lookup portal for archived statutory data if full migration is deferred.
### Do you support migration to cloud ERPs other than Tally (e.g., NetSuite, Zoho Books, Dynamics 365)?
Yes. The extraction, transformation, and reconciliation methodology is target-agnostic. We have delivered migrations to NetSuite, Zoho Books, Microsoft Dynamics 365 Business Central, and custom cloud stacks. The CoA mapping, tax-code cross-walk, and parallel-run discipline remain identical; only the load APIs and target validation scripts change.
### What happens if we find data errors after go-live?
The 30-day hypercare period covers post-go-live defects at no extra cost. Errors traced to migration logic (mapping, transformation, load scripts) are fixed immediately. Errors rooted in source-data quality (e.g., wrong GSTIN on a 2022 invoice) are logged, corrected in the target via adjustment vouchers with audit trail, and the correction procedure is documented for the statutory auditor. A formal project closure sign-off closes the liability window.
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Published 2026-09-23 · © 2026 TACHY SCHOOL ERP · School ERP in India