GDPR Legitimate Interests: When UK Businesses Can Rely On Them

If you run a small business, there’s a good chance you process personal data every day - customer enquiries, supplier contacts, employee records, website analytics, CCTV footage, marketing lists, and more.

Under the UK GDPR (and the Data Protection Act 2018), you can’t just collect and use personal data because it’s “useful”. You need a lawful basis.

One lawful basis that comes up a lot for UK businesses is relying on legitimate interests under GDPR (sometimes referred to as “GDPR legitimate interest”). It can be a practical option, but it’s also one of the easiest to get wrong if you treat it like a “catch-all”.

Below, we’ll walk through what legitimate interests is, when it works, when it doesn’t, and the steps you should take to rely on it in a way that’s defensible if you ever face a complaint, a subject access request, or an ICO query.

What Does “Legitimate Interests” Mean Under UK GDPR?

“Legitimate interests” is one of the six lawful bases for processing personal data under Article 6 of the UK GDPR.

In plain English, it means you can process personal data if you have a genuine, justifiable business reason to do so, and that reason isn’t overridden by the individual’s interests, rights, and freedoms.

For small businesses, legitimate interests can be appealing because:

• It can cover “everyday business” processing that isn’t strictly contractual.
• It doesn’t require you to capture consent in every scenario (which can be operationally messy).
• It can be used for some marketing activities (but not all, and not without care).

But there’s a catch: you’re expected to think it through and be able to show your working. That’s where many businesses stumble.

Legitimate Interests Isn’t A Free Pass

It’s tempting to label nearly any processing as “legitimate interests” and move on.

In reality, legitimate interests works best when:

• The processing is something a person would reasonably expect from you; and
• The impact on privacy is limited and proportionate; and
• You can offer clear opt-outs and safeguards where appropriate.

If your processing is unexpected, intrusive, high-risk, or involves sensitive categories of data, legitimate interests is often not the right route (or at least it requires much more careful handling).

When Can A UK Business Use Legitimate Interests Under GDPR?

To rely on legitimate interests, you generally need to be able to answer three questions:

• Do you have a legitimate interest? (A real business or operational need.)
• Is the processing necessary? (More than just useful or routine - it should be a proportionate way to achieve that purpose.)
• Do the individual’s interests override yours? (Would the processing be unfair, unexpected, or harmful?)

These questions are often packaged into what’s commonly called a Legitimate Interests Assessment (LIA), which we’ll cover next.

Common Scenarios Where Legitimate Interests Often Fits

Every business is different, but legitimate interests is commonly used for:

• Fraud prevention and security (including protecting your systems and customer accounts).
• Network and information security (logging, monitoring, access controls).
• Customer relationship management (keeping records of interactions, following up on queries).
• Business administration (internal reporting, management oversight, improving processes).
• Some types of direct marketing, especially to existing customers (but this is nuanced and overlaps with PECR).

If you’re dealing with workplace data, you may also be thinking about monitoring tools, acceptable use rules, and device policies - this is where having a clear Acceptable Use Policy can be part of demonstrating transparency and fairness.

When Legitimate Interests Is Usually Not The Best Choice

Legitimate interests is less likely to be appropriate where:

• You’re processing special category data (like health data) - you typically need an additional condition under Article 9, and you should be especially cautious.
• You’re processing data about children or other vulnerable individuals.
• You’re doing anything unexpected (for example, collecting data for one purpose and then using it for another without telling people properly).
• You’re relying on legitimate interests to avoid giving people a real choice where consent is actually required (particularly in marketing and cookies contexts).

As a practical rule: the more intrusive the processing, the harder it is to justify under legitimate interests.

How Do You Rely On Legitimate Interests Properly? (The LIA Step-By-Step)

If you want to rely on legitimate interests in a way that stands up to scrutiny, documenting a Legitimate Interests Assessment (LIA) is often a sensible approach.

You don’t have to publish your LIA, but you should keep it on file as part of your accountability obligations (and you may want it ready if the ICO ever asks questions).

Step 1: The Purpose Test (What’s Your Legitimate Interest?)

Start by describing:

• What you’re trying to achieve (e.g. preventing fraud, improving services, ensuring security).
• Why it matters to your business (and, where relevant, to your customers).
• Who benefits (is it purely commercial, or does it also protect users?).

Keep it specific. “Running our business” is usually too vague. “Preventing fraudulent card use and account takeovers” is much clearer.

Step 2: The Necessity Test (Is This Processing Actually Needed?)

Ask yourself:

• Is the processing reasonably necessary for the purpose, or is it just convenient?
• Is there a less intrusive way to achieve the same result?
• Can you minimise what you collect (data minimisation) and how long you keep it?

This is where a lot of LIAs fail in practice - businesses sometimes jump straight to “we want this data” without testing whether it’s proportionate.

Step 3: The Balancing Test (Do The Individual’s Rights Override Yours?)

This is the heart of the assessment. You’re weighing your interest against the person’s privacy expectations and risks.

Consider:

• Reasonable expectations: Would a customer reasonably expect you to use their data in this way?
• The nature of the data: Is it basic contact info, or something more sensitive?
• Impact: Could it cause distress, discrimination, financial harm, or loss of control?
• Safeguards: Can you reduce risk through access controls, encryption, short retention periods, and clear opt-outs?

If you’re using surveillance tools, for example, it’s vital to be extra careful. Even if CCTV is common, adding audio recording can raise risk significantly - and you’ll want to think carefully about privacy impacts and transparency (including signage and policies) if you’re considering anything like CCTV with audio.

Step 4: Document And Implement (Don’t Stop At Paperwork)

An LIA isn’t just a “tick-box” exercise.

Once you’ve decided legitimate interests applies, you should also implement what your assessment relies on, for example:

• Update your privacy information so people understand what’s happening.
• Put opt-outs in place (where relevant), and make sure they actually work.
• Limit access internally on a “need to know” basis.
• Set retention periods, then stick to them.

In many cases you’ll also need to make sure your contracts with suppliers are compliant - especially where a third party processes personal data on your behalf. This is where a proper Data Processing Agreement becomes a key part of doing things properly.

Practical Examples: Legitimate Interests For Marketing, Workplace Monitoring, And AI Tools

Legitimate interests comes up most often in a few “real world” small business areas. Here’s how to think about them.

1) Direct Marketing To Existing Customers (Proceed Carefully)

Legitimate interests is often used as a GDPR lawful basis for some forms of marketing, but you need to keep two things in mind:

• UK GDPR lawful basis (where legitimate interests may apply); and
• PECR rules (which can require consent or a “soft opt-in” for certain electronic marketing, especially for individuals).

For example, emailing existing customers about similar products may be possible (depending on the details), but you should still give an easy opt-out and be transparent about it.

Where you’re using cookies or similar tracking, PECR usually requires consent for non-essential cookies (even if you might rely on legitimate interests for associated processing under GDPR), so consent is often the safer and more appropriate route.

2) Workplace Monitoring And Device Policies

If you have staff, you may want to monitor systems for security, prevent data leakage, or manage productivity. Legitimate interests might apply, but employees have strong privacy expectations at work too.

If your team uses personal devices for work, you’ll want to be especially cautious - for example, policies around device use, monitoring, and separation of personal/work data can be crucial. This is where thinking about work phones vs BYOD becomes part of your privacy risk management.

And don’t forget: transparency matters. Even if your intention is legitimate (like security), hidden monitoring is more likely to be seen as unfair.

3) Using AI Tools With Business Data

Many small businesses now use AI tools for drafting, summarising, customer service, and internal efficiency. If personal data is going into these tools, you still need a lawful basis and you still need to comply with the core GDPR principles (fairness, transparency, data minimisation, security).

Before you rely on legitimate interests here, it’s worth stepping back and checking what data is being shared, whether it’s necessary, and what the vendor does with it. Concerns about confidentiality and privacy are common, and issues like retention and re-use of inputs are exactly why businesses ask whether ChatGPT GDPR compliance steps are needed in their workflows.

In many cases, a written internal policy and supplier due diligence are just as important as picking a lawful basis.

What Do You Need To Tell People If You’re Using Legitimate Interests?

Even when legitimate interests applies, you still have strong transparency obligations.

That typically means your privacy information should clearly explain:

• What personal data you collect;
• What you use it for;
• The lawful basis you rely on (including “legitimate interests” where relevant);
• What those legitimate interests are (in plain English);
• Who you share data with (if anyone);
• How long you keep it; and
• The individual’s rights, including the right to object to processing based on legitimate interests.

For most small businesses, this is done through a well-drafted Privacy Policy and (where relevant) just-in-time notices (for example, a CCTV sign, or a short notice on a form).

Don’t Forget The Right To Object

One key point with legitimate interests is that individuals have the right to object to processing based on legitimate interests.

If they object, you can’t just ignore it. You must stop processing unless you can demonstrate compelling legitimate grounds that override the person’s interests, rights, and freedoms (or the processing is needed for legal claims).

From a business perspective, this is another reason to keep your LIA tidy and practical - if you ever need to justify why you continued processing, you’ll want a clear record.

Be Ready For Subject Access Requests

If someone asks what data you hold about them, legitimate interests doesn’t let you sidestep that request. You’ll still need a process for responding within the required timeframes (and handling exemptions properly).

Having a plan for subject access requests can save you a lot of stress if a request lands in your inbox unexpectedly.

Key Takeaways

• Legitimate interests can be a practical lawful basis for everyday business processing, but it isn’t a “free pass” - you need to be able to justify it.
• To rely on legitimate interests properly, you should work through the purpose test, necessity test, and balancing test (often documented as a Legitimate Interests Assessment).
• Legitimate interests often fits for areas like security, fraud prevention, customer admin, and some marketing, but you need to be careful where processing is intrusive or unexpected.
• Transparency is essential - your privacy information should clearly explain what you do, why you do it, and that you’re relying on legitimate interests.
• Individuals have the right to object to processing based on legitimate interests, so your approach needs to be fair, proportionate, and defensible.
• Where you use suppliers to process data, make sure your contracts (including a Data Processing Agreement) match what’s actually happening in your business.

If you’d like help reviewing your lawful basis for processing, preparing a Legitimate Interests Assessment, or getting your policies and contracts in place, you can reach us at 08081347754 or team@sprintlaw.co.uk for a free, no-obligations chat.