What Is Legitimate Interest in B2B Marketing?
What is legitimate interest in B2B marketing? It is one of the most misunderstood concepts in UK data protection law, yet it underpins a large proportion of lawful business-to-business outreach.
Many SMEs assume that consent is required for all marketing activity. Others believe that because they are contacting businesses rather than consumers, the rules do not apply at all. The reality sits between those two extremes.
Legitimate interest is one of the lawful bases under UK GDPR. It allows a business to process personal data where there is a genuine commercial reason to do so, provided that the processing is proportionate and does not override the individual’s rights.
In practical terms, legitimate interest is often the legal foundation that makes structured B2B outreach possible. It is commonly relied upon when:
• Contacting decision-makers in relevant roles
• Sending targeted cold emails to corporate addresses
• Using purchased B2B data responsibly
• Conducting proportionate lead generation campaigns
Understanding what legitimate interest in B2B marketing actually means can remove a great deal of uncertainty. It can also help you avoid both unnecessary fear and unnecessary risk.
In this guide, we will explain what legitimate interest is, when it applies, when it does not apply, how it interacts with cold email and purchased data, and what practical steps UK SMEs should take to rely on it properly.
The Short, Direct Explanation
Legitimate interest in B2B marketing is a lawful basis under UK GDPR that allows you to process personal data without consent, provided you have a genuine commercial reason and your actions are proportionate.
That is the simple version.
Under UK GDPR, there are six lawful bases for processing personal data. Consent is only one of them. Legitimate interest is another, and in a business-to-business context, it is often the most appropriate.
When you contact a decision-maker at a limited company about a service that is relevant to their role, you are usually relying on legitimate interest rather than consent.
However, legitimate interest is not automatic. You must be able to justify it.
To rely on legitimate interest in B2B marketing, you should be able to answer three basic questions:
• Is there a genuine commercial purpose behind this outreach?
• Is contacting this individual necessary to achieve that purpose?
• Is the impact on the individual minimal and reasonable?
If the answer to those questions is yes, legitimate interest may apply.
If your outreach is broad, irrelevant or excessive, it becomes harder to justify.
Legitimate interest is not a loophole. It is a structured framework that balances commercial activity with individual rights.
In the next section, we will break down how the legitimate interest test works in practice and what the three-part assessment involves.
The Three-Part Legitimate Interest Test
To rely on legitimate interest in B2B marketing, you should apply what is commonly known as the three-part test.
This is not about creating complex legal paperwork. It is about structured thinking.
The three parts are:
-
Purpose test
-
Necessity test
-
Balancing test
Let’s break each one down in practical terms.
1. The Purpose Test
Ask yourself:
Do we have a genuine and lawful business reason to process this data?
In a B2B context, this could include:
• Introducing a relevant product or service
• Generating sales conversations
• Expanding into a new market
• Promoting a commercially aligned offering
Cold outreach to relevant decision-makers is generally considered a legitimate commercial activity. The ICO recognises that direct marketing can constitute a legitimate interest.
However, the purpose must be real and specific. “We want to email everyone just in case” is not a strong purpose.
2. The Necessity Test
Ask:
Is processing this specific personal data necessary to achieve our purpose?
For example:
If you are selling HR software, contacting HR Directors may be necessary. Contacting unrelated departments may not be.
Necessity does not mean there are no alternative methods at all. It means the processing is a reasonable way of achieving your objective.
If your campaign relies on thousands of loosely related contacts with minimal segmentation, it becomes harder to argue necessity.
3. The Balancing Test
This is the most important part.
Ask:
Does our commercial interest outweigh any potential impact on the individual?
In B2B marketing, the impact is usually low when:
• The communication is relevant
• The message is professional
• The volume is controlled
• There is a clear opt-out
The impact becomes higher when:
• The outreach is persistent
• The content is misleading
• The recipient has no logical connection to the offer
• Opt-out requests are ignored
If a reasonable business professional would expect to receive this type of communication in their role, your balancing test is stronger.
Documenting the Test
You do not need a 30-page legal document.
For most SMEs, a short internal note covering:
• Your purpose
• Why the data is necessary
• Why the impact is minimal
is sufficient.
This is sometimes referred to as a Legitimate Interest Assessment.
Applying the three-part test makes legitimate interest in B2B marketing defensible rather than assumed.
In the next section, we will examine when legitimate interest does not apply and where caution is required.
When Legitimate Interest Does Not Apply
Legitimate interest in B2B marketing is powerful, but it is not universal.
There are situations where relying on legitimate interest becomes weak or inappropriate. Understanding these limits is just as important as understanding when it applies.
1. When the Role Is Not Relevant
If you contact someone whose job role has no meaningful connection to your offer, your balancing test becomes weak.
For example:
• Emailing a Facilities Manager about advanced tax planning
• Contacting a junior assistant about enterprise software
• Sending mass outreach without role filtering
If the communication is not aligned with the recipient’s professional responsibilities, it becomes harder to argue that your interest outweighs their right not to be contacted.
Relevance is central to legitimate interest in B2B marketing.
2. When Outreach Becomes Excessive
Legitimate interest depends on proportionality.
If you:
• Send repeated emails after no engagement
• Combine email, phone and LinkedIn messages in quick succession
• Continue outreach after objections
the balance shifts.
The more intrusive your approach, the harder it becomes to justify.
3. When Dealing With Sole Traders
Sole traders blur the line between business and personal identity.
Under PECR, they are often treated more like individuals than corporate entities. That means consent may be required in some circumstances.
Even where legitimate interest may still apply under GDPR, you should apply greater caution.
If your dataset contains a large number of sole traders, your compliance approach may need to be more conservative.
4. When Processing Sensitive Data
Legitimate interest is rarely appropriate when processing special category data, such as:
• Health information
• Political beliefs
• Religious affiliation
B2B marketing rarely requires this type of data, but it is worth stating clearly. Sensitive data requires additional safeguards and is not suited to general outreach.
5. When Expectations Are Unreasonable
The balancing test considers what an individual would reasonably expect.
If a senior decision-maker in a relevant industry receives a professional, targeted introduction, that is generally within expectations.
If someone in an unrelated role receives repeated unsolicited contact, that may fall outside reasonable expectations.
The concept of reasonable expectation is often what separates compliant outreach from intrusive behaviour.
Legitimate interest in B2B marketing is strongest when outreach is targeted, relevant and controlled.
It weakens when volume replaces logic.
In the next section, we will look at how legitimate interest connects specifically to purchased B2B data and cold email campaigns.
How Legitimate Interest Applies to Purchased B2B Data
One of the most practical questions SMEs ask is how legitimate interest in B2B marketing applies when using purchased data.
If you buy a B2B contact list and begin outreach, you are processing personal data. That means you must identify a lawful basis. In most B2B scenarios, that lawful basis is legitimate interest.
The key point is this:
Buying the data does not create legitimate interest.
Your commercial purpose and structured use of the data does.
Purchased Data and Lawful Basis
When using purchased B2B data, you should be able to explain:
• Why you are targeting that specific industry
• Why the job roles selected are relevant
• Why your product or service aligns with those roles
• Why contacting them is proportionate
For example:
If you purchase a list of Operations Directors in UK manufacturing firms because you offer operational efficiency software, your purpose and necessity tests are clear.
If you purchase a broad database with minimal filtering and send generic outreach to thousands of contacts, your justification weakens.
The legitimacy of your interest is strengthened by clarity and segmentation.
Due Diligence Still Matters
Relying on legitimate interest does not remove your responsibility to understand how the data was sourced.
Before using purchased data, you should:
• Understand the supplier’s sourcing approach
• Review data fields for relevance
• Ensure your outreach aligns with professional expectations
• Prepare a clear opt-out process
If you are evaluating the broader question of data legality, see our guide on whether buying B2B data is legal in the UKfor a full overview of the compliance framework.
Legitimate Interest and Cold Email
Legitimate interest is often the foundation behind compliant B2B cold email.
If you are unsure how email-specific rules apply, you can read our detailed breakdown of is cold emailing businesses legal in the UK.
In most corporate B2B scenarios, legitimate interest supports the processing of the data, while PECR governs the sending of the email itself.
Understanding the distinction between these two layers removes much of the confusion.
The Commercial Discipline Factor
Using legitimate interest properly requires discipline.
You should:
• Avoid overbuying data
• Segment before sending
• Limit follow-up frequency
• Document your reasoning
When legitimate interest in B2B marketing is applied thoughtfully, it enables structured outreach rather than blocking it.
If you want a broader explanation of the overall legal position, see our guide on whether buying B2B data is legal in the UK.
In the next section, we will outline a practical template you can use to document legitimate interest within your organisation.
A Simple Legitimate Interest Assessment Template for SMEs
You do not need a legal department to rely on legitimate interest in B2B marketing.
What you do need is evidence that you have thought it through.
A Legitimate Interest Assessment, often shortened to LIA, is simply a structured record of your reasoning. For most SMEs running B2B outreach, this can be a short internal document covering the three-part test.
Below is a practical framework you can use.
Step 1: Define the Purpose Clearly
Write a short statement explaining:
• What you are trying to achieve
• Who you are targeting
• Why this outreach supports your commercial goals
Example:
“We are contacting Marketing Directors at UK-based software companies to introduce our data-driven lead generation services, which are directly relevant to their role.”
This anchors your purpose in relevance rather than volume.
Step 2: Explain Why the Processing Is Necessary
Document why contacting this specific audience is necessary.
For example:
• These job roles are responsible for marketing strategy and lead generation.
• Email outreach is a reasonable and proportionate method of introduction.
• There is no equally effective alternative that does not involve processing their business contact data.
You are not required to prove that there are no other methods at all. You are demonstrating that your approach is reasonable in context.
Step 3: Conduct the Balancing Test
Ask:
Would the individual reasonably expect to receive this type of communication in their professional role?
Then record:
• Why the impact is minimal
• How you limit frequency
• How opt-outs are handled
• How you ensure relevance
For example:
“The outreach is limited to two emails over a defined period. Each email clearly identifies our company and includes an unsubscribe option. Contacts are limited to senior decision-makers in relevant roles.”
This shows proportionality.
Step 4: Record Safeguards
List the controls you have in place:
• Role-based targeting
• Industry filtering
• Suppression list management
• Privacy notice published on your website
• Regular data review and cleaning
These safeguards demonstrate responsibility.
Step 5: Review Periodically
Legitimate interest is not a one-time decision.
If your targeting changes or your campaign expands significantly, revisit your assessment.
A simple annual review is usually sufficient for most SMEs.
Why This Matters
If you are ever asked to justify your approach, having a short documented assessment shows that your use of legitimate interest in B2B marketing was deliberate and structured.
It turns an abstract legal concept into a defensible commercial process.
In the final section, we will summarise the key points so you can review the essentials quickly.
Executive Summary: Legitimate Interest in B2B Marketing
If you want the essentials in one place, here is the clear summary.
What is legitimate interest in B2B marketing?
It is a lawful basis under UK GDPR that allows you to process personal data without consent, provided your commercial purpose is genuine, necessary and proportionate.
When Legitimate Interest Applies
• You are contacting decision-makers in relevant roles
• Your product or service aligns with their professional responsibilities
• The communication is reasonable in a B2B context
• You provide a clear and simple opt-out mechanism
• You respect objections and suppression requests
In most structured B2B outreach campaigns, legitimate interest is the lawful basis relied upon.
The Three Questions You Must Answer
Before relying on legitimate interest, ask:
-
Do we have a clear commercial purpose?
-
Is contacting this individual necessary to achieve it?
-
Is the impact on them minimal and reasonable?
If you cannot answer those clearly, your approach needs refining.
When Caution Is Required
• When contacting sole traders
• When roles are not clearly relevant
• When outreach becomes excessive
• When sensitive data is involved
• When there is no documentation of your reasoning
Legitimate interest weakens when relevance and proportionality weaken.
Practical Safeguards
• Define your ideal customer profile
• Segment by role and industry
• Limit follow-up frequency
• Maintain suppression lists
• Record a short Legitimate Interest Assessment
Structure protects both compliance and reputation.
The Core Principle
Legitimate interest in B2B marketing is not a loophole. It is a balancing exercise.
When outreach is relevant, transparent and disciplined, legitimate interest supports lawful B2B lead generation in the UK.
If your process is vague, excessive or undocumented, risk increases.
Used correctly, legitimate interest allows UK SMEs to operate commercially without relying solely on prior consent.
