The verdict in three sentences
Migration, not the software itself, is the real risk of a switch: a botched mapping can corrupt years of entries. A structured method (audit, mapping, reprise, parallel run) costs 5,000 to 20,000 EUR over 4 to 8 weeks. The parallel run, where old and new tools run side by side, is the insurance that avoids downtime.
The steps of a damage-free migration
A successful migration follows control gates. At each step you validate before moving on: you never switch over without a numeric reconciliation.
| Step | Duration | Deliverable | Control gate |
|---|---|---|---|
| Data audit | 3 to 5 d | Source mapping | Volumetry validated |
| Field mapping | 5 to 8 d | Correspondence table | Rules approved |
| History reprise | 1 to 2 wk | Migrated data | Balances reconciled |
| Parallel run | 2 to 3 wk | Controlled dual entry | Gaps < 0.5% |
| Cutover and close | 2 to 4 d | Go-live | Partner sign-off |
Cost and price drivers
Budget depends on volume, the cleanliness of source data and the number of fiscal years to migrate. Clean data and a single year pull the price down; ten years of history and several sources pull it up.
| Factor | Simple migration | Complex migration |
|---|---|---|
| Years migrated | 1 to 2 | 5 to 10 |
| Number of sources | 1 | 3+ |
| Data condition | Clean | Needs cleanup |
| Estimated 2026 cost | 5,000 to 9,000 EUR | 12,000 to 20,000 EUR |
| Duration | 4 to 5 wk | 7 to 8 wk |
| Parallel run | 2 wk | 3 wk |
Mini case study
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Nadia, director of a 16-person firm in Lyon, migrates 8 years of history and 3 data sources to a new tool. The vendor quotes 16,000 EUR with a 3-week parallel run. During that window, detected gaps (0.3%) are fixed before cutover, avoiding a hot migration that would have cost several days of downtime. Result: zero lost history, the next closing unaffected, and a 16,000 EUR cost against the ~25,000 EUR risk of a failed migration (re-keying, delays, client disputes).
FAQ
Can we lose history during migration? With an upfront audit, balance reconciliation and a parallel run, the risk of loss is nearly nil: nothing switches over without a numeric control.
How long without the new tool? No downtime with a parallel run: the old tool stays operational until the new one is fully validated.
Do we need to migrate all history? Not always: often the last 2 to 3 years are migrated in detail and the rest as balances, cutting cost without losing useful information.
Who signs off the cutover? Partners sign off on reconciled balances and a parallel-run gap below 0.5%, never on a mere impression.
What is the main cost item? Mapping and data cleanup: heterogeneous or dirty sources account for most of the gap between a 6,000 and an 18,000 EUR migration.
Let's scope your project. Send us the years to migrate, your sources and the target tool, and we will price your migration with a parallel run. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
