What Does Migration Away from Microsoft Cost? A Cost and Effort Analysis
Date: May 5, 2026 | Research in the context of ongoing migration programs in France (DINUM), Schleswig-Holstein, the German federal government (ZenDiS/openDesk) and Switzerland (Center SDS, PoC BOSS)
1. Core Question and Methodology
The question "what does migration away from Microsoft cost?" cannot be answered with a single number, but only through comparison of three cost curves:
- Microsoft status quo — ongoing license, cloud and service costs, with documented steep growth dynamics.
- Open source migration costs — one-time investments plus temporary parallel operation.
- Open source steady state — ongoing costs for support, internal development, personnel, training.
Reliable figures are available from several major projects: Schleswig-Holstein (ongoing), Munich's LiMux (2003–2017, plus re-migration), French Gendarmerie (GendBuntu, since 2008), DINUM plans 2026, City of Zurich and Swiss federal administration. The figures have different scopes depending on the source — licenses vs. TCO, migration vs. lifecycle, technical conversion vs. organizational project. This makes direct comparability difficult. Nevertheless, trends and orders of magnitude are recognizable.
Therefore, the clean separation between the following is important:
- directly documented government figures,
- media reports and secondary sources,
- analyst estimates,
- model calculations in this article.
2. Status Quo: What Microsoft Costs (Comparison Basis)
Switzerland
| Entity | Cost Item | Source / Classification |
|---|---|---|
| Swiss Federal Government 2009 | CHF 42 million contract | Stürmer/BFH via Blick |
| Swiss Federal Government 2026 | CHF 140 million Microsoft expenses; tripling in around 15 years | ditto / media report |
| City of Zurich 2019 | CHF 7 million | Tagesanzeiger / Blick |
| City of Zurich 2026 | CHF 28–31 million; multiplication | Tagesanzeiger 23.01.2026 |
| City of Zurich license framework agreement until 2030 | up to CHF 108 million; 83 million administration + 25 million schools | inside-it.ch 07.02.2025 |
| Swiss authorities 2015–2026, cloud total | CHF 3.2 billion, of which 1.3 billion Microsoft | Tagesanzeiger 01.02.2026 |
| Swiss Army, additional M365 costs | CHF 4.6 million/year for 12,000 accounts | Süssli letter / Tagesanzeiger |
German Federal Government
| Data Point | Source / Classification |
|---|---|
| Federal administration expenses for software licenses and IT services: 2022 around EUR 771 million → 2023 over EUR 1.2 billion (+57%) | GI press release 30.04.2025 |
| Federal administration Microsoft expenses: according to GI almost quintuple in seven years | GI press release 30.04.2025 |
Note: The figure of EUR 771 million or over EUR 1.2 billion does not refer exclusively to Microsoft license costs, but to expenses for software licenses and IT services overall. The Microsoft-specific statement is the almost five-fold increase in federal expenses for Microsoft products within seven years reported by GI.
General Growth Dynamics
Microsoft announced price changes for several Microsoft 365 packages effective July 1, 2026; depending on the package, the increases are in the single-digit to low double-digit percentage range. This confirms the structural property of the model: Microsoft 365 is not a one-time purchase, but a rental model with recurring and potentially increasing costs.
For 100,000 users, this can result in annual license costs on the order of several tens of millions of euros. A simple extrapolation from Schleswig-Holstein — around EUR 500 per person per year in license savings × 100,000 users — would yield EUR 50 million per year. This figure is not a universally applicable TCO metric, but a scaling of the currently most publicly prominent reference case.
3. Concrete Migration Costs — Case Studies with Figures
3.1 Schleswig-Holstein: Currently the Strongest Publicly Documented Reference Case
Key data: Migration since 2024, state's open source strategy, phased replacement of Microsoft components. By the end of 2025, according to the state government, nearly 80% of workplaces outside the tax administration were working with LibreOffice. The state government also reported the migration of almost 44,000 email mailboxes to Open-Xchange.
| Item | Amount / Value |
|---|---|
| One-time migration and further development investment 2026 | EUR 9 million |
| Annual license savings from 2026 compared to Microsoft 365 | more than EUR 15 million |
| Calculated per-capita license savings with 30,000 workplaces | approx. EUR 500/person/year |
| Funding for 17 open source projects separately | just under EUR 3 million |
| Calculated license-side payback | under 1 year |
Source: State Chancellery Schleswig-Holstein, "Digital Sovereignty is Possible and Economical", 04.12.2025; supplementary Borncity, Medium (Can Artuc), heise.
Important regarding scope: The publicly communicated 9 million euros and 15 million euros refer to the investment and savings framework for 2026 mentioned by the State Chancellery. They are not automatically a complete TCO calculation over all previous years, specialized applications, personnel and parallel operation costs.
What these figures do not fully include:
- Personnel and preparation costs in previous years, including building coordination, pilot projects and organizational structures.
- Costs of areas still bound to Microsoft, especially the tax administration and other Windows-only specialized applications.
- Indirect costs of common platform and suite development via Dataport or North German administrative cooperations.
- Costs for specialized applications, identity management and long-term operational organization, if these are not included in the 2026 investment framework.
Assessment: Schleswig-Holstein is not important because all figures would be complete, but because for the first time an ongoing European administrative project publicly states a clear relationship between one-time investment and annual license savings.
3.2 French Gendarmerie: GendBuntu as Completed Long-Term Project
Key data: Migration since 2004/2008, own Ubuntu variant, more than 100,000 workplaces, staged conversion over many years.
| Item | Value |
|---|---|
| Direct license savings per year | around EUR 2 million |
| TCO reduction per workplace | around 40% according to case studies |
| Migration duration | around 13 years in phases |
| Critical success rule | Migrate applications before operating system |
Sources: Wikipedia GendBuntu, Major Stéphane Dumond (LibreCon Bilbao 2014), case studies and secondary reports.
Most important lesson: The direct license savings of about EUR 2 million per year for around 100,000 devices correspond to only about EUR 20 per device per year. This seems low compared to today's Microsoft 365 costs, but is historically explainable: The Gendarmerie migrated at a time when primarily classic Office and Windows licenses were being replaced, not a fully developed Microsoft 365 cloud subscription stack.
The reported TCO reduction of around 40% therefore resulted not solely from license avoidance, but from extended hardware lifecycles, lower client resource requirements, standardized maintenance and more stable support costs.
3.3 Munich LiMux: Case Study for Governance, Not Just Technology
Key data: around 15,000 workplaces, migration 2003–2013, political re-migration from 2017.
| Source | Linux Costs | Microsoft Costs Hypothetical / Real |
|---|---|---|
| City of Munich, own calculation 2012 | EUR 23 million | EUR 34 million |
| HP study commissioned by Microsoft 2013 | EUR 60.7 million | EUR 17 million |
| Re-migration to Windows 2017–2022 | — | EUR 50–86 million |
Breakdown of re-migration according to 2017 city council document:
- Licenses: EUR 29.9 million
- External consulting: EUR 24 million
- IT service provider it@M: EUR 13.4 million
- Personnel costs: EUR 14 million
- Hardware: EUR 4.8 million
Discrepancy analysis: The large difference between the City of Munich and HP study is essentially explained by different assumptions about migration of specialized applications. If all specialized applications must be completely ported to Linux, costs explode. If they can continue to be operated via terminal server, web application or transitional architecture, the calculation turns out significantly different.
This distinction — how radical is the migration in specialized applications? — is one of the most dominant cost drivers of any migration and the point at which TCO studies diverge most strongly.
Lesson: LiMux was neither simple proof of open source affordability nor a simple specter of impossibility. The most important lesson is governance: A partially completed migration that is politically reversed can be the most expensive option.
3.4 France DINUM 2026: Political Scaling Plan, Budget Still Unclear
Key data: On April 8, 2026, DINUM announced the exit of its own workplaces from Windows in favor of Linux and demanded plans from all ministries to reduce dependence on non-European IT and cloud providers. Eight domains are affected: operating system, collaboration, antivirus, AI, databases, virtualization, cloud and networks.
| Item | Classification |
|---|---|
| DINUM pilot | own DINUM workplaces as "Live Proof of Concept" |
| Potential scaling | Media reports mention up to 2.5 million workplaces in the entire administration |
| Time horizon | frequently classified in media and analyses as until 2029/2030 |
| Total migration costs | Analyst estimate: EUR 1.5–3 billion over 5–7 years |
| Per workplace from this | EUR 600–1,200 over the entire migration period |
| Caisse nationale d'Assurance maladie | around 80,000 employees use Tchap/Visio/FranceTransfert |
| Public cloud procurement 2025 | EUR 84 million, 70% European according to media reports |
Sources: DINUM announcement, heise online 10.04.2026, Borncity, ghacks, Tech-insider.
Important classification: The figure of EUR 1.5–3 billion is not a publicly confirmed DINUM budget figure, but an analyst or secondary estimate. It should be understood as an order of magnitude, not as a reliable budget allocation.
Lesson: France is politically significant because the migration is not formulated as an isolated Linux project, but as an industrial, security and sovereignty policy program. Whether the plan works out economically depends on implementation, procurement, ministerial coordination and specialized applications.
3.5 German Federal Government / ZenDiS / openDesk
Key data: ZenDiS was founded in 2022, openDesk is being built as a sovereign alternative to Microsoft 365.
| Item | Value / Classification |
|---|---|
| ZenDiS personnel 2024 | 9 employees, 4 of them in development |
| ZenDiS federal funds 2024 on contract basis | around EUR 19 million, mainly OpenCoDE |
| Contract volume provided for openDesk by February 2025 | EUR 950,000 |
| Contract volume provided for OpenCoDE by February 2025 | EUR 550,000 |
| OSBA demand minimum requirement | EUR 30 million/year |
| BMI budget title openDesk 2023 | EUR 21.6 million |
| Remaining amount 2024 released by budget committee but reportedly not paid out | EUR 34 million |
| openDesk Enterprise licenses productively in use | around 70,000 according to ZenDiS framework contract announcement |
Sources: netzpolitik.org 11.03.2024, Behörden Spiegel 25.03.2025 and 02.04.2025, FSFE, OSBA 12.08.2025, GI 30.04.2025, ZenDiS.
German lesson: The ZenDiS example shows not that open source would be too expensive, but that a national open source infrastructure can hardly generate economies of scale without adequate basic financing and clear rollout commitment. Underfunding and lack of coordination thus become cost risks themselves.
3.6 Swiss Federal Government: Status of Preliminary Work
| Data Point | Value / Classification |
|---|---|
| M365 rollout completed | Mid-December 2025, around 54,000 workplaces |
| Proof of Concept BOSS (Office Automation OSS) | Start early 2025, first results mid-2026 |
| BFH study CEBA | Backend and frontend services examined |
| Planned OSS test environment 2024 | 30 workplaces |
| Federal Court Zimbra | around CHF 25/user/year for 600 users, 1 person administration according to reference reports |
| Center SDS | Launch 28.04.2026, 31 founding members, more than CHF 200,000 own funds |
| Project "State Center for Digital Sovereignty" | CHF 4 million as requested or planned project; financing not to be treated as permanently secured basic financing |
Sources: admin.ch 18.12.2025, Netzwoche, BFH study 31.05.2024, inside-it.ch, Swissinfo, clarus.news dossier on Center SDS 29.04.2026.
Specific Swiss situation: Switzerland only broadly rolled out M365 in 2025 and is now examining open source alternatives with a time delay. This is a special case: The investments in M365 are still young, while Cloud Act, data protection, EMBAG and sovereignty issues are running in the background.
4. Comparative Calculation: Cost per Workplace
The most sensible normalization is comparison per workplace, because the migration masses are very different in size.
Attention: The following values mix one-time costs, ongoing costs, historical TCO data and estimates. They are rough orientation values, not a TCO calculation in the narrower sense.
| Case | Workplaces | One-time Migration Costs | Per Workplace | Methodology |
|---|---|---|---|---|
| Schleswig-Holstein 2026 | 30,000 as calculation basis | EUR 9 million | approx. EUR 300 | Only investment year 2026; without complete preliminary and specialized application costs |
| France 2026–2030 | up to 2,500,000 according to media | EUR 1.5–3 billion | EUR 600–1,200 | Analyst estimate, 5–7 years |
| LiMux City of Munich 2012 | approx. 15,000 | EUR 23 million | EUR 1,533 | Self-calculation, approx. 10 years |
| LiMux HP study 2013 | approx. 15,000 | EUR 60.7 million | EUR 4,047 | Microsoft contract study, 10 years, extensive specialized application porting |
| LiMux re-migration to Windows | approx. 15,000 | EUR 50–86 million | EUR 3,333–5,733 | 5 years |
| Case | Workplaces | License Savings/Year | Per Workplace/Year |
|---|---|---|---|
| Schleswig-Holstein | 30,000 as calculation basis | more than EUR 15 million | approx. EUR 500 |
| Gendarmerie | approx. 100,000 | approx. EUR 2 million | approx. EUR 20, direct licenses only |
| Gendarmerie incl. TCO | approx. 100,000 | approx. 40% TCO reduction | variable depending on baseline TCO |
| France DINUM estimate | 100,000 as comparison unit | EUR 1–2 million | EUR 10–20, licenses only |
Notable finding: The Schleswig-Holstein figure is significantly higher than the Gendarmerie figure. This is not necessarily due to more efficient migration, but mainly to different historical starting positions. The Gendarmerie mainly replaced classic Office and Windows licenses. Schleswig-Holstein is replacing components of a significantly more expensive Microsoft 365 cloud stack.
The cost increase of the Microsoft stack itself is therefore a central value driver of today's migration calculations.
5. Cost Components: Where the Real Expenses Arise
A serious calculation must show these components separately.
5.1 Costs Directly Avoidable Through Migration
- Microsoft 365 subscriptions
- Windows client licenses
- Server and