SaaS vs PaaS vs IaaS: The Differences Explained for SMEs

SaaS, PaaS and IaaS. Three acronyms that come up in almost every cloud conversation and that, in practice, are still often used interchangeably. For an SME owner who simply wants to know what they're buying and what they're still responsible for, that's confusing. In this article we explain what SaaS, PaaS and IaaS are, how responsibility is split between you and the cloud provider, what each model costs, and which choice suits an SME in which situation.

What is a cloud service model, exactly?

A cloud service model determines how much of your stack the provider takes over and where your own work begins. In a traditional on-premises setup, you're responsible for everything: building, power, servers, operating system, patches, application and data. As soon as you consume something as a service from the cloud, part of that stack moves to the provider. Exactly where that line falls is the difference between IaaS, PaaS and SaaS.

The three models form an ascending scale. With IaaS, the provider takes care of the physical infrastructure and you do the rest. With PaaS, the provider also manages the operating system and runtime, so all you supply is your application and data. With SaaS, the application is fully ready and you only need to set up users, data and configuration.

IaaS: your virtual server room

Infrastructure as a Service is exactly what the name promises: infrastructure delivered as a service. Think Azure Virtual Machines, AWS EC2 or Google Compute Engine. You rent compute, storage and networking from a data centre and install your own operating system, applications and data on top. The provider keeps the hardware running; you make sure the OS is patched, backups are set up properly and your apps keep working.

IaaS is attractive if you have a specific workload that doesn't simply fit into a SaaS subscription. Think of an old ERP system that only runs on Windows Server, or a test environment you want to scale up and down quickly. For SMEs, IaaS is more often a step in a migration journey than a final destination. Businesses weighing up on-premises server or cloud often opt for a hybrid setup, with a small part on IaaS and the rest moved to SaaS.

Cost model: pay-as-you-go per hour or per minute, with discounts of up to 65 percent through Azure Savings Plans for 1- or 3-year commitments. If nobody keeps an eye on which virtual machines are still running, the bill quietly climbs. That's why properly outsourcing cloud management is a necessity rather than a luxury with IaaS.

PaaS: a ready-made development platform

Platform as a Service is the model in which the provider also manages the operating system, middleware and runtime. Examples include Azure App Service, Azure SQL Database, Azure Functions and Heroku. You supply your code, choose a scale, and the provider makes sure it runs, gets patched and autoscales neatly. That saves a developer or administrator a lot of work.

For most SMEs, PaaS only comes into play when something is being built, either in-house or by a partner. A custom online shop, a customer portal, an integration between accounting software and CRM, an AI-based application: these are almost always cheaper and more secure on PaaS than on your own VM. An Azure App Service Standard S1 plan (the lowest tier with autoscaling) costs around $57 a month, excluding database and integrations. Not exactly pocket change, but manageable for a specific application.

If you're planning to have custom software built, it pays to ask the "IaaS or PaaS" question early. Choosing PaaS often saves years of maintenance, because you never have to touch the OS again.

SaaS: ready to use, by subscription

Software as a Service is the model most SMEs work in every day without giving it a second thought. Microsoft 365, Google Workspace, Exact Online, Salesforce, HubSpot, Dropbox, TeamViewer: all SaaS. You open a browser or app, log in and get to work. The provider runs the servers, handles updates, patches vulnerabilities and delivers new features.

For SMEs, SaaS is the most practical choice in almost every case. No server room, no evenings spent patching, no backup scripts that quietly stopped running two years ago. According to Statistics Netherlands (CBS), 71 percent of Dutch businesses with more than ten employees used the cloud in 2024, as did 49 percent of businesses with 2 to 10 employees. That puts the Netherlands well above the EU average.

The business model is a subscription per user per month. From 1 July 2026, Microsoft 365 Business Basic rises from $6 to $7 per user per month (in US dollars), an increase of roughly 16 percent. Business Standard goes from $12.50 to $14, and Business Premium stays at around $22. For existing customers, the new prices only apply at the first contract renewal after 1 July 2026. Our guides to the Microsoft 365 price increase in 2026 and choosing Microsoft 365 licences help you use that increase as an opportunity to review your licence mix.

The shared responsibility model in plain English

Every cloud service model comes with a shared responsibility model: a table that sets out exactly who maintains and secures which layer. In simplified form:

• IaaS. The provider takes care of the building, power, cooling, hardware and virtualisation. You're responsible for the operating system, patches, network configuration, applications, data, identities and access.
• PaaS. The provider also takes over the operating system and runtime. You keep the application, data, identities and access.
• SaaS. The provider runs virtually everything. You're responsible for data, identities, access and configuration.

The catch lies in "virtually". Even with SaaS, the customer remains accountable for its own data, access and account security. A hacked Microsoft 365 account is almost never Microsoft's fault. It's a user who clicked on a phishing email and didn't have MFA switched on. In the cloud you hand the infrastructure over to the provider, but identity remains yours.

Which model suits which situation?

There's no single right answer, but there are a few good rules of thumb for SMEs:

1. Standard processes (email, calendar, accounting, CRM, payroll, HR). Almost always choose SaaS. Faster, more secure and cheaper over 5 years than hosting it yourself.
2. An application that's only available as an installation. Choose IaaS, unless the vendor also offers a cloud version.
3. Having your software partner build something for you. Choose PaaS. Less maintenance, better scalability and faster releases.
4. A large workload with predictable usage. IaaS with a 1- or 3-year savings plan can be considerably cheaper than pay-as-you-go.
5. Data that absolutely must stay in the Netherlands. Combine with the Azure regions Netherlands North or West Europe, or choose a specific Dutch SaaS provider.

Costs in practice: it's rarely about the sticker price

The hourly rate of a virtual machine or the monthly price of a licence says little about the real costs. What puts an SME in control of its cloud bill is a combination of three factors: clear agreements on who manages which environment, a licence mix that matches actual usage, and shadow IT that doesn't quietly balloon.

Research by Torii estimates that the average business uses more than 100 SaaS applications and that around 61 percent of them were purchased outside IT. For an SME, the gains therefore usually come from clearing things out, not from buying more. A six-monthly licence optimisation delivers savings of 15 to 25 percent for many customers. See also our guides on cutting IT costs and the risks of shadow IT.

Vendor lock-in and the EU Data Act

If you choose SaaS or PaaS, you become dependent on a specific provider. Your data sits in the provider's format, and your integrations run on its APIs and its way of working. That's called vendor lock-in, and for years it was a strong card in the hands of the big cloud players.

Since 12 September 2025, the EU has curbed this with the EU Data Act. Cloud providers must remove barriers to switching, customers can terminate contracts with two months' notice, and between September 2025 and January 2027 egress charges may only cover actual costs. From 12 January 2027 they may no longer be charged at all. For SMEs that's tangible news: switching is demonstrably becoming easier.

Compliance and data residency

GDPR compliance doesn't depend on the model you choose, but on where your data is stored, who can access it and how you can demonstrate that it's properly arranged. Microsoft completed its EU Data Boundary on 26 February 2025. Customer data and pseudonymised personal data from Microsoft 365, Azure and Dynamics 365 are processed within the EU and EFTA. For most SMEs, that's more than enough for GDPR compliance.

If you choose American SaaS services outside that boundary, the US CLOUD Act deserves attention. A US court can compel a US provider to hand over data, even if that data is stored in Europe. For sensitive sectors (healthcare, finance, government), that's regularly a reason to opt for a European SaaS alternative or a private cloud setup. See also our guide to complying with GDPR in practice.

Frequently asked questions about SaaS, PaaS and IaaS

What is the difference between SaaS, PaaS and IaaS in one sentence?

IaaS means renting virtual infrastructure on which you install your own software, PaaS is a ready-made platform on which you run your own application, and SaaS is a complete, working application you subscribe to. The higher up that stack you go, the less the provider asks of you, but the less control you have over the underlying technology.

Which model is best for SMEs?

For standard processes (email, calendar, accounting, CRM, HR), SaaS is the best choice in almost every case. Quick to set up, no server management and almost always cheaper over 5 years. IaaS is useful for specific legacy applications, while PaaS mainly plays a role in custom software.

Is SaaS always cheaper than your own server?

No. For a large, stable, always-on workload, a well-maintained server can sometimes be cheaper, especially if you own the licences. More often, though, SaaS works out cheaper because there are no more server, licence and maintenance costs on top. Calculate over 5 years and factor in security, backup, patching and downtime.

Who is responsible for the security of my data in the cloud?

In every model, you as the customer are responsible for your data, your identities and your access. The provider secures the infrastructure; you secure the configuration and the users. Whatever the model, a phishing-prone account with weak passwords is the customer's risk, not the provider's.

Does the EU Data Act change my choice?

Yes. Since September 2025, a provider may no longer make switching difficult, and from January 2027 egress charges disappear entirely. That makes vendor lock-in less severe from a legal point of view. Technical lock-in remains a real issue, though: moving data out of a specific data format isn't always trivial.

Conclusion

SaaS, PaaS and IaaS aren't competing technologies but three levels of handing things over. The higher you climb, the less you manage yourself and the more dependent you become on the provider. For SMEs, SaaS is the most practical choice in most cases, PaaS the standard for custom software, and IaaS the fallback for legacy or very specific workloads. The real gains rarely lie in the model itself but in sharp choices: a licence mix that matches actual usage, tight identity management, a demonstrably GDPR-compliant setup and a clean-up of shadow IT.

Want a fresh pair of eyes on your cloud landscape to see which workloads belong in SaaS, PaaS or IaaS? TRON Group helps Dutch SMEs with managed IT, Microsoft 365 and Azure setups that fit their size and risk profile. Call +31 85 303 5869 or visit our managed IT services page. We'll map out your current situation, advise where SaaS is the best choice and where PaaS or IaaS add value, and make sure your cloud bill stays predictable instead of being a surprise every month.