The verdict in three sentences
An accounting firm migrating from legacy software (installed desktop app, local server under the desk) to a hosted platform should budget USD 44,000-77,000 for build and configuration, plus USD 10,000-18,000 for data migration. The project fits in 12-18 weeks when the chart of accounts and permanent files migration is scoped from day one. The real risk is not technical but calendar-based: a botched migration during tax season costs more than the project itself.
What the migration actually costs
The budget breaks into three blocks: application build, data migration and the parallel run. In New York, at a USD 580/day rate, here is the 2026 order of magnitude for a firm of 8 to 20 staff.
| Line item | 2026 range (USD) | Detail |
|---|---|---|
| Build & configuration | 44,000 – 77,000 | Production, review, client portal modules |
| Data migration | 10,000 – 18,000 | Chart of accounts, trial balances, permanent files |
| Parallel tax run | 6,600 – 12,000 | 1 to 2 months running in parallel |
| Team training | 3,900 – 6,600 | 2-3 sessions + onboarding support |
| Annual maintenance | 12% of build/year | Fixes, enhancements, version upgrades |
The parallel run is the line firms most underestimate: running the old and new systems side by side for one or two cycles avoids a hard cutover.
Migrating the chart of accounts and permanent files
Migration is not just exporting trial balances. Each client file carries history — engagements, fixed assets, carry-forwards, VAT settings — that must be mapped to the new data model.
| Migrated element | Typical volume (300-client firm) | Effort |
|---|---|---|
| Chart of accounts + variants | 300 charts | High (1-to-1 mapping) |
| Permanent files | 300 files | High (documents + metadata) |
| Historical entries | 3 to 5 fiscal years | Medium (structured import) |
| Fixed assets | ~4,000 lines | Medium |
| VAT/filing parameters | per file | High (manual check) |
The golden rule: freeze the scope at N years of migrated history and archive the rest read-only. Migrating 10 years of entries triples the migration bill for near-zero practical value.
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Mini case study
Evelyn, partner at a 14-person firm in New York, migrates from a 2011 installed app to a hosted solution. Build at USD 62,000, data migration at USD 14,000, two-month parallel run at USD 9,000, totaling USD 85,000. Each staff member recovers 6 hours/week lost to manual syncing and re-keying. Across 14 people at a loaded cost of USD 42/hour, that is ≈ USD 14,100/month of recovered capacity. The project pays back in 6 months, before counting the peace of mind during tax season — which ran without a single interruption.
FAQ
Can we migrate without shutting the firm down? Yes, via a parallel run: the old software stays read-active for 1-2 months while the new one takes over production. Budget USD 6,600-12,000 for this phase, essential outside tax season.
How many years of history should we migrate? 3 to 5 years covers 90% of cases. Beyond that, migration becomes read-only archiving and cost climbs 30-60% with no real business value.
What is the main risk? The calendar. A cutover mistimed during tax season can block filings. We always schedule go-live between June and September.
Custom build or off-the-shelf software? It depends on your specifics. A custom build at USD 44,000-77,000 is justified if your processes fall outside the standard; otherwise a configured vertical costs less.
What maintenance budget should we plan? Maintenance at 12% of build per year, roughly USD 5,500-9,200/year for this firm size, covers fixes, enhancements and version upgrades.
Let's scope your project. Tell us your current software, your file count and your window outside tax season, and we'll price build, migration and 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.
