Checklist:
Migrating to Odoo in 30 days

Phase 2. Configuration (weeks 2-3)

Configuring Odoo is faster if you separate master data (products, customers, suppliers, chart of accounts) from processes (flows, automations). Start with master data because, without it, you can't test anything.

• Create the Odoo instance (odoo.sh recommended for 80% of cases)
• Configure the company, the chart of accounts and Spanish taxation (PGC, IVA, withholdings)
• Activate modules according to Phase 1 (not all at once — only the main ones first)
• Configure users and permission groups
• Customise essential views, fields and automations (Studio or Python)
• Configure emails (alias support@, info@, IMAP/SMTP connection)
• Configure payment gateways if you sell online (Redsys, Stripe, Bizum)
• Validate with the internal lead before continuing
• Activate VeriFactu (l10n_es_verifactu) and test invoice issuance

Phase 3. Data Migration (week 3)

This is where most projects get delayed. The cause: underestimating the quality of data from the old system. Reserve time to clean them.

• Export from your current system (Sage, Holded, A3, SAP B1, Gestión Click): customers, suppliers, products, pending accounting entries
• Clean the data: duplicates, obsolete records, inconsistent fields
• Map old fields → Odoo fields (especially accounting accounts and categories)
• Upload to an Odoo test environment (NEVER directly to production)
• Validate balances point by point: the accounting balance matches between the old system and Odoo
• Validate customer and supplier balances (receipts/payments)
• Validate stock by warehouse and product
• Validate the historical open orders
• Decide the cut-off point (end of month / end of quarter / end of year)
• Full backup of the old system before cut-off

Phase 4. Go-live and support (week 4 onwards)

The go-live day is the most stressful. But if you have done phases 1 to 3 well, it should pass without incidents. The first 4 weeks after go-live are critical for detecting and correcting problems.

• Final data load (with balances as of the cut-off date)
• Training for teams by department (practical sessions with real data)
• Documentation of key processes (screenshots + steps)
• Rollback plan defined (in case something critical fails in the first 48 hours)
• Communication to external customers and suppliers about the change (new portal URLs, new invoices)
• Validation with the AEAT in the first month (VeriFactu submission, bank reconciliation, first VAT declaration)
• Review session after 2 weeks: what works, what doesn't, and what to prioritise for future improvements?
• Activate secondary modules (the desirable ones from phase 1) once the operations are stable
• Define the pace of monthly support: hours, SLA, preferred channel
• Quarterly review with the internal manager to identify improvement opportunities

Common mistakes this guide saves you from

• Migrating everything at once — Better to start with accounting+invoicing and add the rest in waves.
• Not cleaning data beforehand — If your Sage has 8,000 customers with duplicates, Odoo will inherit them all.
• Skipping the test environment — Testing in production is expensive; any error remains in the accounting books.
• Training at the end of the project — By the time they reach go-live, the team has already forgotten what they learned.
• Not appointing an internal lead — Without someone to decide internally, the project gets stuck in approvals.
• Ignoring VeriFactu — Mandatory in 2026. Configuring it in phase 2 avoids last-minute rush.
• Not measuring KPIs before and after — Without a starting point, you won't know if the migration improved anything.