Verifying supplier compliance with secure software requirements: a practical guide for UK SMEs

When you buy software, you are not only buying features. You are also taking on part of the supplier’s security posture, development discipline, and maintenance habits. For UK SMEs, that matters because a weak supplier can introduce risk into customer data, internal systems, and day-to-day operations long after the contract is signed.

Verifying supplier compliance with secure software requirements does not need to be a heavyweight exercise. In most cases, the goal is simple: understand what the supplier actually does, what evidence supports their claims, and whether the level of assurance is proportionate to the importance of the software you are buying.

This guide sets out a practical approach for procurement, IT, and business owners who need to make sensible decisions without turning every purchase into a full audit.

What supplier compliance means in secure software procurement

In this context, compliance means that the supplier can show they follow the secure software requirements you set for the product or service. That may include secure development practices, testing, vulnerability handling, dependency management, and incident response. It is not just a statement that the supplier “takes security seriously”.

For SMEs, the key distinction is between a claim and evidence. A claim is a promise. Evidence is something you can review, compare, and record. Examples include documented processes, test summaries, sample reports, and contract terms that require ongoing security obligations.

Why this matters for UK SMEs

Many SMEs rely on software suppliers for core business functions such as finance, HR, customer management, logistics, or specialist industry tools. If that software is poorly developed or poorly maintained, the impact can be wider than a technical issue. It can affect service delivery, customer trust, and recovery costs.

SMEs also tend to have limited time and fewer specialist staff. That makes it tempting to accept supplier assurances at face value. A better approach is to focus on a small set of meaningful checks that reveal whether the supplier’s security maturity matches the risk you are taking on.

How to distinguish security claims from evidence

A useful rule is to ask, “What would we need to see to believe this?” If a supplier says they run secure development practices, ask for the artefacts that show how those practices work in reality. If they say they manage vulnerabilities quickly, ask how they triage issues, what their response times are, and whether they can show examples of the process in action.

Be cautious with broad statements such as “industry standard security”, “enterprise grade protection”, or “fully compliant”. These phrases may be true in a limited sense, but they do not tell you what controls exist, how consistently they are applied, or whether they fit your use case.

Define the secure software requirements before you assess suppliers

Supplier checking is much easier when you know what you are looking for. Before you send a questionnaire or review a proposal, define the minimum secure software requirements for the product or service. Keep the list short, practical, and tied to risk.

For example, a low-risk internal tool may only need basic secure development practices, patching commitments, and a clear vulnerability reporting route. A customer-facing platform handling sensitive data may need stronger testing, more detailed assurance, and tighter contractual obligations.

Set minimum controls and acceptable evidence

Start by deciding which controls are non-negotiable for your organisation. Typical areas include:

• Secure coding and peer review practices
• Security testing before release
• Vulnerability management and patch timelines
• Dependency review and third-party library control
• Access control for development and production environments
• Incident reporting and notification expectations

For each control, define what acceptable evidence looks like. That might be a policy, a process summary, a sample report, or a contract commitment. You do not need every internal document, but you do need enough to judge whether the supplier is operating in a controlled way.

Align requirements to business risk and system criticality

Not every supplier deserves the same level of scrutiny. A sensible way to scale the process is to consider:

• What data the software will process
• How critical the software is to business continuity
• Whether the supplier hosts or operates the service
• How much integration it has with your other systems
• Whether the software is customer-facing or internal only

The more sensitive the data and the more important the service, the more assurance you should ask for. This keeps the process proportionate and helps you focus effort where it matters most.

What evidence to ask suppliers for

Good supplier assurance is based on a mix of documents, answers, and practical demonstrations. You are looking for enough evidence to understand how the supplier builds, tests, and maintains the software, not a perfect stack of paperwork.

Policies, secure development practices, and testing evidence

Useful evidence often includes:

• A secure development policy or lifecycle summary
• Evidence of code review or approval before release
• Security testing summaries, such as application testing or vulnerability scanning
• Details of how findings are tracked and fixed
• Training or awareness arrangements for developers

If the supplier has formal secure development practices, ask how they are applied in day-to-day work. A policy is only useful if it is followed. You are trying to understand whether security is built into the delivery process or added as an afterthought.

SBOMs, vulnerability handling, and dependency management

For many products, especially software with multiple components, ask about dependency management. Dependencies are third-party libraries or packages that the product relies on. They can introduce risk if they are outdated, poorly maintained, or vulnerable.

An SBOM, or software bill of materials, is a structured list of software components used in a product. It can help you understand what is inside the software and support faster response if a vulnerability is identified later. Not every supplier will provide a full SBOM in every case, but for higher-risk software it is a useful assurance artefact.

Also ask how the supplier monitors vulnerabilities, how quickly they assess new issues, and how they decide whether a fix is needed. A strong answer will describe a repeatable process, not just a general commitment to “monitor security advisories”.

How to review supplier responses without overcomplicating it

It is easy for supplier reviews to become long questionnaires that no one has time to assess properly. A simpler method is often better. Create a small scoring approach based on the controls that matter most to you, then review the supplier’s answers against the evidence provided.

Use a simple scoring approach

For example, you could score each area as:

• Meets requirement
• Partially meets requirement
• Does not meet requirement
• Evidence not provided

This gives you a practical way to compare suppliers and identify where follow-up is needed. It also helps you avoid overreacting to minor gaps while still highlighting material weaknesses.

Keep notes on why you gave each score. That makes it easier to revisit the decision later, especially at renewal or if the business changes.

Spot gaps, vague answers, and unsupported assurances

Some common warning signs are easy to miss if you are moving quickly. Watch for answers that are:

• Too generic to be meaningful
• Focused on commercial benefits rather than control details
• Missing dates, owners, or process steps
• Supported only by marketing material
• Inconsistent across different parts of the response

If a supplier says they test regularly, but cannot explain what type of testing is done or how issues are tracked, that is a gap. If they say they manage vulnerabilities quickly, but will not commit to a response timeframe, that is also a gap.

Questions to ask during procurement and renewal

Good questions are specific enough to reveal how the supplier works, but not so detailed that they become a burden for either side. The aim is to understand the controls that matter to your risk, not to interrogate every technical detail.

Questions about development, testing, and release controls

Useful questions include:

• How do you build security into your development process?
• What checks happen before code is released?
• Do you use code review, automated testing, or both?
• How do you handle security findings from testing?
• How do you manage third-party libraries and updates?

These questions help you understand whether the supplier has a repeatable process. If they answer with broad statements, ask for examples or supporting documents.

Questions about incident handling and ongoing maintenance

You should also ask:

• How do customers report security issues?
• What is your process for triaging vulnerabilities?
• How do you decide the urgency of a fix?
• How do you notify customers about material security issues?
• How long do you support the software, and what happens at end of life?

These questions are especially important at renewal. A supplier that was acceptable two years ago may no longer meet your expectations if the product has changed, the data it handles has expanded, or the supplier’s own risk profile has shifted.

How to handle higher-risk suppliers and exceptions

Some suppliers will need more scrutiny than others. That is normal. Higher-risk suppliers might process sensitive data, provide business-critical services, or have deep technical integration with your environment.

When to request additional assurance

Ask for additional assurance when the software is important to operations or when the initial evidence is weak. That may include more detailed testing results, a walkthrough of the development process, a sample incident communication, or a clearer commitment to patching and support.

You can also ask for contractual commitments where appropriate, such as notification of material vulnerabilities, support periods, or obligations to maintain key security controls. Keep the wording practical and focused on what you need to manage risk.

How to document risk acceptance and follow-up actions

If a supplier does not fully meet your requirements but the business still wants to proceed, document the decision clearly. Record:

• What requirement was not met
• Why the exception is being accepted
• Who approved the decision
• What compensating controls are in place
• What follow-up action is required and by when

This is not about creating bureaucracy. It is about making sure the business understands the trade-off and does not forget it later. Exceptions should be time-bound and reviewed, not left open indefinitely.

Building supplier verification into your wider governance

Supplier assurance works best when it is part of normal governance, not a one-off exercise at contract signature. The most effective SMEs build a light but repeatable process that connects procurement, risk management, and periodic review.

Link procurement checks to risk management and reviews

Keep a record of supplier risk ratings, key evidence, review dates, and any open actions. That makes it easier to track whether a supplier remains suitable over time. It also helps when staff change, because the rationale is already documented.

For important suppliers, review the assurance at set intervals or when something changes, such as a major product update, a new hosting arrangement, a security incident, or a material change in the data being processed.

Keep the process proportionate for SME teams

SMEs do not need a large vendor risk programme to get value from supplier verification. A short checklist, a standard evidence request, and a simple review log are often enough to improve decision-making. The key is consistency.

If you are buying software regularly, consider creating three tiers of supplier review: low, medium, and high risk. That allows your team to spend more time where the exposure is greater and avoid overchecking low-risk purchases.

Common mistakes to avoid

Most supplier assurance problems come from a few familiar habits. The good news is that they are easy to improve once you know what to look for.

Relying on marketing statements alone

Marketing material can be useful as a starting point, but it should never be the only source of assurance. A polished website does not tell you how the supplier actually develops, tests, or supports the software.

Always ask for evidence that is specific to the product or service you are buying.

Treating one-off checks as ongoing assurance

Security is not static. Suppliers change their code, their hosting, their staff, and sometimes their ownership. A supplier that looked fine at onboarding may need a fresh review later.

Build in periodic checks, even if they are light-touch. That gives you a better chance of spotting changes before they become problems.

Practical starting point for UK SMEs

If you want a simple way to begin, use this sequence:

1. Define the software’s business criticality and data sensitivity.
2. Set a short list of minimum secure software requirements.
3. Ask for evidence, not just assurances.
4. Score the response using a simple and consistent method.
5. Record gaps, exceptions, and follow-up actions.
6. Review higher-risk suppliers again at renewal or when circumstances change.

That approach is usually enough to improve supplier decisions without slowing the business down.

If you would like help shaping a proportionate supplier assurance process, or want to align procurement checks with a broader information security governance approach, speak to a consultant.

Frequently asked questions

What evidence should an SME ask for when checking secure software suppliers?

Ask for evidence that shows how the supplier develops, tests, and maintains the software. Useful items include a secure development policy, testing summaries, vulnerability handling processes, dependency management details, and, for higher-risk products, an SBOM. The right level of evidence depends on the sensitivity and criticality of the software.

How often should supplier secure software assurances be reviewed?

Review them at least at renewal, and sooner if the supplier, the software, or your use of it changes in a material way. For higher-risk suppliers, periodic reviews during the contract term are sensible. The aim is to keep assurance current, not to rely on a check that is already out of date.