What Is Software as a Service? SaaS Explained for UK Firms

A growing SaaS stack can leave UK companies paying for overlapping subscriptions while business data becomes scattered across multiple platforms. Software as a service can make things simpler in terms of access and infrastructure, yet it can lead to redundancies if it isn’t monitored on a consistent basis.

Answering “What is software as a service?” makes it easier to distinguish convenient subscription-based software from a stack that eventually becomes costly to maintain. This approach can cut infrastructure and deployment costs, but its effectiveness depends on how the software is priced and integrated.

This guide covers how SaaS operates, its difference from PaaS and IaaS, which models fit various business requirements, how much UK organisations are charged for it, and what things need to be considered in relation to UK GDPR, data residency, and vendor termination.

In many cases for businesses in the UK, SaaS operates side-by-side with a solution developed for that particular business by software development companies in the UK. It is not about whether the tool provided through a particular approach is better or worse overall, but what the business needs.

Below is the table which summarises the key SaaS facts to consider in evaluation: ownership, cost, deployment time, appropriate usage, risk of compliance in the UK, and the point where licence and integration costs make sense for a bespoke solution.

Software as a Service (SaaS) is software accessed over the Internet while the provider hosts, maintains and updates the application on its own or third-party infrastructure. Customers access the software as a managed service and may pay through subscriptions, usage-based charges, freemium plans, or other pricing models.

Practical considerations relate to where the software operates and who controls its operation. The vendor takes care of application and infrastructure operations in SaaS solutions, while the client pays for access to such systems. 

This matters when deciding whether to buy SaaS or choose a software development company to build around your workflows.

How SaaS differs from traditional on-premises software

The main point of difference here is that the former type is managed by the software provider, whereas the latter type of software is installed by the user. All other differences in terms of SaaS vs. on-premise are related to cost, support, customisation, infrastructure management, and exit strategy, and largely stem from this operational model.

When comparing SaaS versus bespoke products from MVP development companies, companies should not consider cost alone at the outset. The more unique the process, integration needs or ownership expectations, the greater the importance of distinguishing software operated by the vendor from software operated directly by the customer.

Key characteristics of the Software as a Service model

There are certain operational characteristics of SaaS platforms that make them different from locally hosted software applications. These characteristics impact the way customers gain access to the software, how updates are delivered by the vendors, and the manner in which costs accrue.

• Multi-tenant architecture. The same software platform can be used by many customers at the same time, ensuring that their accounts and data are kept logically isolated from each other.
• Subscription billing. The subscription-based model for SaaS is usually based on monthly or annual charges based on users, plans, or usage. The initial expenditure becomes low, but there will be a continuous obligation, which means that the costs can increase over time.
• Automatic updates. Vendors implement patches and new features centrally rather than requesting each customer to update their software. This helps to minimise maintenance efforts but also limits business discretion over release schedules and interfaces.
• Browser or app access. Users will generally be able to get to the software through a web browser, desktop application or mobile application without having to install the software on their own computer.

From boxed licences to cloud subscriptions

Before the advent of SaaS, firms used to purchase software licences, install software on their own and do the upgrading. In the latter half of the 1990s, the concept of application service provider emerged, wherein business applications were hosted remotely. This was a precursor to the concept of SaaS.

Browser CRM technology was made popular by Salesforce in the early 2000s through their approach to providing business applications without any need for local installation. This was due to advancements in internet technology and cloud computing, which made it easier to use hosted applications and thus subscription delivery.

The contemporary SaaS model was a result of this change: software vendors provide the service constantly, and customers pay to use the product without having to buy each release separately. 

APIs, integrations and why they break

SaaS solutions do not exist in a vacuum, as the data from CRM may have to be transferred into accounting software, the HR system may have to interface with payroll systems, and the support system may have to transfer data to analysis tools. This can be accomplished through API integrations.

In some cases, integration effort, middleware, and maintenance can end up being more expensive than the actual subscription fees themselves. The underlying software framework, API design, and authentication model can affect how much custom integration work is required. 

The differences between SaaS, PaaS, and IaaS lie in the amount of the technological stack managed by the provider. The choice will be determined based on whether your company requires pre-made software, an environment for creating apps, or complete control of computing resources.

These models are not conflicting with each other. A firm that is using custom software development services can deliver an application on PaaS or IaaS while using SaaS for CRM, accounting, communication, and other general purposes of business.

When SaaS is the right choice

Using software as a service for business is most appropriate when the procedure is common among businesses, and there is no commercial benefit in having that particular software built from scratch. These circumstances are mostly applicable to SaaS:

• The workflow is standard. Email, accounting, CRM, HR, and project management systems seldom require fully proprietary software, which is why a ready-made SaaS solution will be sufficient to meet the basic requirements.
• The team is small. The boutique company is able to save effort on server maintenance, deployment processes, and infrastructure support because these tasks are undertaken by the vendor.
• You need to start quickly. Such applications do not require long-term development and are useful in situations where the firm requires the system to be operational even before its customised version is completed.

When you need PaaS or IaaS instead

Both PaaS and IaaS can be considered as appropriate approaches when the SaaS solution fails to offer sufficient flexibility to the organisation. This occurs when an agency develops its own product, requires customised infrastructure, or has some other technical requirements that cannot be met by the SaaS solution.

SaaS choice influences implementation level, pricing model, integration requirements, and how well the software aligns with current operations. Horizontal SaaS solutions are typically evaluated by cost, usability, and integration, while vertical SaaS solutions require evaluation of industry processes and compliance reporting.

Horizontal SaaS: tools every business uses

Horizontal SaaS involves those functions which are common to different industries. The software as a service examples clearly depict how the same category can support a retailer, law firm, or agency without being designed around one sector:

• Email and collaboration. Email, calendar, file storage, document editing, and team collaboration are incorporated in Microsoft 365 and Google Workspace.
• CRM. HubSpot and Salesforce help with contact management, sales pipeline, customer activity, automation, and reporting.
• Accounting. Invoicing, accounting, reconciliations, and reporting are taken care of by Xero and QuickBooks. 
• Project management. It is handled by Asana, Monday.com, and Microsoft Planner.
• HR. These functions are performed by HiBob, BambooHR, and CharlieHR.

Vertical SaaS: industry-specific platforms

Vertical SaaS products cater to the terminology and workflow of the specific industry. The organisation will begin with a solution that already fits into the industry workflow, meaning there will be less configuration necessary for the platform.

Examples include:

• legal practice management systems for cases, time tracking, and billing clients; 
• healthcare systems for patient administration and clinical processes;
• fintech applications for payments and finance; 
• recruiting and applicant tracking systems; 
• logistics management systems for fleets/shipments;
• construction management systems.

SaaS in regulated UK sectors

It is essential for financial services, law, and healthcare firms to evaluate the capabilities of the SaaS solution to store regulated data before using the software. Evaluation should consider factors like access controls, auditing, encryption, data retention policies, and data-exporting capabilities instead of relying on the vendor’s feature list.

Key areas to review include:

• Role-based access: the ability to restrict permissions by roles, groups, clients, matters, or types of data.
• Audit trails: allowance for the system to track users who accessed, modified, exported, or deleted any information and when.
• Encryption: the method of encryption used for data both in transit and at rest, including backups where applicable.
• Retention policy: the ability to maintain, archive, and delete records in accordance with legal and internal policies.

The advantages and disadvantages of SaaS become more apparent once you consider the aspect of purchasing software through a subscription service. SaaS might be faster and more efficient in terms of set-up and scalability, but the cost is that you will have some of your control handed over to the software vendor.

Key benefits for UK businesses

The main benefits of software as a service come from reducing the amount of infrastructure and maintenance a business has to manage itself. There are more details on how it impacts your product:

• Faster deployment. In most cases, teams can begin the work by configuring accounts and importing data rather than buying the required servers and installing software individually on every machine.
• Lower upfront cost. SaaS eliminates big upfront costs associated with buying software or infrastructure by switching to regular charges. This way, companies with fewer resources will be able to implement software without spending lots of money at first.
• More predictable monthly spending. Subscription pricing gives finance professionals a clearer starting point for calculating costs, especially for user-based licence fees. But for an accurate total cost of ownership (TCO) calculation, organisations should also factor in other costs such as implementation, integration, support, and renewal fees.
• Updates are handled by the provider. Patching, feature releases, and maintenance are typically handled from the central site. The internal IT staff spends less time on version updates, but firms have to ensure that the upgrades do not impact processes or integration.
• Capacity can follow team size. The process of adding licences tends to be less complex than extending the on-premises infrastructure. This can be particularly beneficial when dealing with an increasing number of people in temporary capacity or on projects.

SaaS limitations and risks to consider

There are savings on operations but also dependencies that are harder than expected to assess at procurement time.

• Service availability is partly outside of your control. If there is a downtime or degradation of any functionality in the cloud provider’s infrastructure, your people may not be able to work even though everything else is fine.
• Renewal costs can rise. The first contract may include introductory pricing or discounts that do not survive renewal. Additional users, higher-tier features, and vendor price changes can also increase the cost without any major change in how the software is used.
• Customisation can have some limitations. While there can be numerous ways of configuring, the core of the product remains the same and is based on the same vendor architecture. Brands with peculiar approval cycles and proprietary logic may run into some problems.

Vendor lock-in: the exit questions to ask before you sign

Before signing up for the service, ask the SaaS provider these questions and get written answers. These will indicate whether you can recover all necessary information, how long it will take to transfer it elsewhere, and any technical or contractual expenses that might arise upon termination of the subscription. Here is what you need to ask your provider:

• What data can we export if we leave?

Are core records, custom fields, configurations, metadata, permissions, and activities also included?

• What export formats do you support?

Verify whether data is exportable to CSV, JSON, XML, and database formats, and whether relationships between records are maintained.

• Does the export process include attachments, audit logs, and activity history?

Some companies export only essential information; attachments, comments, and logs need a special request.

• Are there any API limitations during migration?

Find out if regular limitations still exist during a massive export or if higher ones are possible for extra payment.

• For how long do you store our information once the contract terminates? 

Confirm when our access to the account ends, when production data is deleted, and how long backups are retained after termination.

• What migration assistance is provided, and what additional charges are there?

Inquire if the provider assists with the data export, technical support, or other migration services, and whether there are any separate fees for that.

The SaaS cost in the UK may be anywhere from just a few pounds per person monthly up to several hundred for business-specific software. The initial headline subscription fee is just the tip of the iceberg, as factors such as the number of users, plan type, billing schedule, etc. may affect the total cost.

Common SaaS pricing models

Not all SaaS companies have the same pricing model. There are many that price their products on a per-user or per-month basis, but there are others that charge based on other models like organisation-level or usage models.

Typical monthly spend for a UK SMB

Software as a service pricing has huge variation between categories, and thus the numbers provided below should be seen as up-to-date sources of information rather than averages. They were compiled from vendor-provided costs and were valid in the UK in September 2026.

Here is an example for further clarification: let’s take a business from the UK with 10 employees that uses Microsoft 365 Business Standard for all employees, Salesforce Starter for 3 salespeople, Xero Grow, CharlieHR, and Planner Plan 1 for all employees.

• Microsoft 365: 10 × 10.80 = £108
• Salesforce: 3 × 20 = £60
• Xero Grow: £39
• CharlieHR for 10–14 people: £45
• Planner Plan 1: 10 × 7.70 = £77

The stack comes to approximately £329 per month before VAT, based on current published prices. For a 50-person team, the resulting subscription can be around £1,510 per month before VAT.

Hidden costs that break the budget

The price displayed on a SaaS pricing page does not reflect all the costs involved in implementing the product. Before comparing vendors, one must include the costs incurred outside the basic license fee:

• Paid integration and API. Some integration plugins will need a higher-tier plan or additional resources from the API.
• Onboarding and migration. Transferring old data, configuring permissions, and rebuilding workflows may create a significant one-time expense across software-as-a-service pricing.
• Staff training. It is possible that staff will require onboarding for the software to provide the desired productivity benefits.
• Premium support. Quick response times, designated account managers, or round-the-clock support can incur extra charges.
• Licence underutilisation. Excess licences will likely be left over when employees, contractors and part-time workers depart.
• Renewal increases. Introductory price discounts may expire, and suppliers may alter list prices between contract periods.
• Value Added Tax (VAT). List prices in the UK are often stated without VAT. The extent to which VAT is a net expense varies by organisation.

It is not the case that the purchase of a seemingly compliant SaaS solution removes your liability for data protection. According to the UK GDPR, and as evidenced in the ICO guidance, if a company acts as a controller, it has an obligation to ensure that processors have appropriate guarantees with regard to the processing of personal data.

This means that in a UK company’s case, the vendor due diligence process should not end with simply spotting a GDPR icon or a privacy policy page link. You need to understand which types of personal data are collected by the software and how they are processed and used.

Controller vs. processor: where your liability sits

In a typical SaaS arrangement, the customer becomes the controller because it determines why personal data is processed and for what purpose the service is used. The SaaS provider is normally the processor when it processes personal data under the customer’s instructions.

Even when employing a processor, the duties of the controller do not get discharged. As the ICO states, controllers should be able to appoint processors that can provide appropriate guarantees regarding technical and organisational measures. In addition, processors are liable for any breach of their duties.

When a controller contracts out processing activities, Article 28 states that the processing must be based on a contract or other legal act. This is usually set out in a Data Processing Agreement (DPA) and includes, but is not limited to, the nature, period, purpose, and type of data being processed.

Where is your data actually stored?

A .co.uk domain or a London office that sells the product does not necessarily indicate where the consumer’s data is processed. The production servers may be located in one place, the backup servers somewhere else, and the support engineers somewhere else.

Inquire of the vendor in writing about the location of primary data, backups, and logging, from where the support staff is able to access it, and which sub-processors will receive any personal information. Do this prior to signing the agreement so that it can be checked along with the DPA and transfer documentation.

A SaaS compliance checklist before you buy

When you are about to sign a SaaS agreement, consider the following issues with regard to the vendor’s documentation and written answers. You need to make sure that the location where your data is stored and who has access to it, the transfer process, data retention period, and termination are considered.

When determining how to choose a SaaS provider, benchmark the potential vendors not on the basis of how many features they have, but rather based on how they function compared to how your company currently operates. Here are some factors that can help differentiate between the two.

Step 1. Start with your actual workflow. See if the software will cater to the approvals, handovers, roles, and exceptions that your team works with on a daily basis. If the regular processes are still done through spreadsheets or manual data entry, then it won’t be very effective for operational use.

Step 2. Test the integration you will actually use. Ask the vendor to demonstrate how the platform integrates with your CRM, ERP, accounting software, identity provider, and analytical tools. Check which integrations are native, which need middleware, and whether API access or webhooks sit behind a higher-priced plan.

Step 3. Get specific about data location. Request the names of countries where production data, backups, and logging take place, as well as the current list of subprocessors of the vendor. The Data Processing Agreement (DPA) must reflect these conditions and describe data retention, deletion, and international transfers.

Step 4. Check what security certificates actually cover. It should not be taken as an ISO 27001 certificate alone being sufficient. Request the scope of certification, confirm whether the software as a service offering falls within that scope, and ask whether the provider is also certified under Cyber Essentials.

Step 5. Read the SLA as a contract, not a marketing claim. Look into how uptime is measured, the maintenance periods that are excluded, and what happens after a major outage. Also, the SLA should mention the response time for critical issues, the escalation process, and any service credits.

Step 6. Ask the vendor to explain the exit process. Identify the type of record, file, and configuration data that you can extract and their formats, how long you have access to export them following termination, and whether migration support services cost additional money. This will help you determine how challenging it is to switch service providers.

Step 7. Build a 3-year cost before signing.  Consider renewal increase rates, expected user numbers, storage requirements, premium functionality, and implementation considerations. Compare the total cost to the initial quotation so the introductory price doesn’t obscure the fact that the final cost will be significantly higher.

Step 8. Test support before you become a customer. Raise an issue that requires technical assistance during UK business hours and time how quickly staff respond. Also check if the response is helpful and how easy it is for the issue to reach an expert. This will give you a better indication than sales response time.

The SaaS model is very successful when the company uses standardised and repeatable processes that do not need to be heavily customised. However, the model is not effective when the company relies heavily on custom and specific business processes, unique logic, or system control.

Considering Software as a Service as a business strategy often results in too many subscriptions and duplication of tools. It is essential for businesses to audit their entire software stack annually, eliminate duplicates, and get rid of any tools not offering sufficient operational value.

Exit strategy planning must happen before signing the contract. Review data export capabilities, data retention policies, termination provisions, migration assistance, and dependencies before signing. An efficiently managed SaaS stack gives the organisation flexibility, but only when procurement and governance processes are managed intentionally.