The verdict in three sentences
For a Berlin software vendor moving from perpetual licences to subscriptions, the shift to multi-tenant SaaS adds 15 to 35 % to development cost, or EUR 8,000 to 30,000 excl. VAT for a mid-sized product. The architecture choice then sets your margin for years: shared database with row-level security at around EUR 1.50 per customer per month, schema per tenant around EUR 4, database per tenant up to EUR 12. For 50 to 500 SME customers, a well-isolated shared database is almost always the right trade-off.
The three multi-tenant models compared
The word SaaS covers very different architectures. The isolation model drives security, hosting cost, ease of upgrades and your sales arguments with demanding IT departments.
| Criterion | Shared database + row-level security | Schema per tenant | Database per tenant |
|---|---|---|---|
| Data isolation | Logical (PostgreSQL RLS policies) | Strong logical (separate schemas) | Physical |
| Hosting per customer per month | EUR 1.50 to 3 | EUR 3 to 6 | EUR 8 to 12 |
| Schema upgrades | One migration for all | One scripted migration per schema | One orchestrated migration per database |
| Practical ceiling | Several thousand customers | 500 to 2,000 schemas | 100 to 300 databases without heavy tooling |
| Restoring a single customer | Complex | Simple | Very simple |
| Argument with an IT department | Average, needs documentation | Good | Excellent |
| Extra development cost | 15 to 20 % | 20 to 28 % | 25 to 35 % |
Many vendors run a hybrid: shared database for SMEs, dedicated database sold as an Enterprise option at EUR 300 to 800 extra per month. That option funds the physical isolation required by hospitals, public bodies or German manufacturers subject to audits.
Detailed migration budget
The extra cost does not come only from the database. You must handle sign-up, recurring billing, observability and compliance. Example for a 60,000-line business application originally built for about EUR 85,000.
| Workstream | Scope | Estimated budget (EUR excl. VAT) | Timeline |
|---|---|---|---|
| Data access refactoring | Tenant ID everywhere, RLS policies or schema routing | 4,000 to 12,000 | 3 to 6 weeks |
| Authentication and account management | SSO, invitations, roles per tenant | 1,500 to 4,000 | 2 weeks |
| Recurring billing | Stripe Billing, plans, trials, compliant invoices | 1,500 to 4,500 | 2 weeks |
| Infrastructure and CI/CD | Containers, environments, per-tenant backups | 1,000 to 4,500 | 2 weeks |
| Migrating existing customers | Import of on-premise databases, migration scripts | 800 to 3,500 | 2 to 4 weeks |
| GDPR compliance and security | Records, standard DPA, encryption, logging | 500 to 1,500 | 1 week |
| Total | 8,000 to 30,000 | 3 to 5 months |
Hosting in Germany (Hetzner, IONOS, AWS Frankfurt) remains a strong sales argument for public and healthcare customers. If you target C5 attestation or work with hospitals, plan for a compliant provider and 20 to 40 % more infrastructure cost.
Impact on revenue and cash flow
Moving to subscriptions creates a cash dip: you collect EUR 1,500 a year instead of a EUR 4,000 licence plus 18 % maintenance. Break-even usually comes between 24 and 36 months, but the vendor's valuation follows annual recurring revenue (ARR), often valued at 3 to 6 times in 2026 for a profitable B2B SaaS, against 1 to 2 times revenue for a licence vendor.
Mini case study
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Julia, CEO of a maintenance management software vendor in Berlin, has 140 on-premise customers. She picks a shared database with RLS, plus a dedicated database option for 8 hospital customers. Migration cost: EUR 22,000. Hosting: 132 customers at EUR 2 plus 8 at EUR 10, or EUR 344 a month. Her technicians spent 30 hours a month installing updates on customer sites at EUR 55 an hour, or EUR 1,650 of avoided cost a month. On that saving alone, the migration pays back in about 17 months, before the subscription effect on valuation.
FAQ
Is row-level security safe enough for sensitive data?
Yes, if every query runs through a connection that sets the tenant ID and automated tests verify isolation. For health or classified data, a dedicated database is preferable, at EUR 8 to 12 more per customer for hosting.
Can we keep an on-premise version for some customers?
Yes, many vendors maintain one for 18 to 24 months. Beyond that, two branches cost 15 to 25 % extra development time.
How long does the full migration take?
Plan 3 to 5 months of development, then 3 to 6 months to move existing customers in waves of 10 to 20.
What subscription price should we set?
A common 2026 rule is 30 to 40 % of the former licence price per year, maintenance included, with an annual commitment.
Do we have to rewrite the whole product?
Rarely. In 70 % of cases, adding a multi-tenant layer and a web interface is enough, without rewriting the business core.
Let's scope your project. Describe your software, customer count and hosting constraints, and we will price your SaaS migration between EUR 8,000 and 30,000, delivered in 3 to 5 months. 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.
