17 Questions to Ask When Hiring a Fractional CTO (UK Founder's Checklist)

Ask fractional CTO candidates about specific businesses they've helped, measurable outcomes they've delivered, how they work with existing teams, and their approach to your specific technical challenges. The right questions separate experienced CTOs who deliver results from consultants who talk strategy but can't execute.

You're interviewing fractional CTOs. Three candidates say similar things: "strategic technology leadership," "align technology with business goals," "prevent costly mistakes."

Which one can actually help your business?

The wrong hire costs £30,000-50,000 in wasted fees plus six months of missed opportunities. A Bristol company paid a fractional CTO £8,000/month for five months before realising they were getting generic advice, not specific solutions. They'd wasted £40,000 and still had the same problems.

These 17 questions separate fractional CTOs who deliver from those who don't.

Questions about their experience and track record

1. "Tell me about three UK businesses similar to ours that you've worked with. What were their challenges and what did you achieve?"

What you're evaluating: Relevant experience with businesses at your stage, in your sector, with similar challenges.

Good answer includes:

• Specific company details (industry, size, revenue)
• Clear problems they faced
• Measurable outcomes achieved
• Timeline for delivering results

Red flag answers:

• Vague descriptions without specific details
• Only worked with much larger or smaller businesses
• No measurable outcomes, just activities ("we implemented agile")
• Only examples from 5+ years ago

Listen for: UK-specific experience. Someone who's only worked with US companies won't understand UK hiring markets, GDPR requirements, or local technology ecosystems.

A Manchester fractional CTO should be able to say: "I worked with a £3M e-commerce business in Leeds. They were struggling with platform stability affecting 15% of orders. We identified their database was undersized, implemented caching, and reduced errors from 15% to 0.3% within six weeks."

2. "What's the biggest technical mistake you've helped a business avoid, and how much did it save them?"

What you're evaluating: Ability to identify and prevent expensive mistakes before they happen.

Good answer includes:

• Specific technical decision they reviewed
• Why the original approach would have failed
• Alternative they recommended
• Financial impact of avoiding the mistake

Example answer: "A £5M SaaS company was about to spend £120,000 rebuilding their authentication system because a developer said it wasn't scalable. I reviewed the code and found it would handle 10x their current load with £15,000 in optimisations. We saved £105,000 and delivered in three weeks instead of nine months."

Red flag: Can't quantify the value they've delivered or only talks about things they built rather than prevented.

3. "What's a situation where you told a client they were wrong about a technical decision? What happened?"

What you're evaluating: Willingness to challenge your assumptions and give honest advice, even when uncomfortable.

Good answer includes:

• Specific situation where client wanted one approach
• Why they disagreed (with technical and business reasoning)
• How they communicated the disagreement
• Outcome of the decision

Listen for: Confidence to disagree with clients whilst explaining reasoning clearly. You're hiring them for expertise, if they just agree with everything you say, they're not adding value.

Red flag: Never disagreed with a client, or disagreed but can't explain why they were right.

Questions about their working approach

4. "How much time would you spend with us each month, and how would that time be structured?"

What you're evaluating: Whether their time commitment matches your needs and they have a structured approach.

Good answer includes:

• Specific days per month (e.g., "3 days per month, typically one day per week")
• How time is allocated (e.g., "2 days with technical team, 1 day on strategic planning")
• Availability outside scheduled days (e.g., "Available on Slack for urgent questions")
• How they handle urgent situations

Red flag answers:

• Vague about time commitment
• "Available whenever you need me" (means they'll be unavailable when you actually need them)
• Only available for scheduled meetings (no flexibility for urgent issues)
• Scheduling 8 hours of meetings for one day (no time for actual work)

Standard fractional CTO engagement: 2-5 days per month, structured as regular weekly or fortnightly sessions, with limited availability between sessions for urgent matters.

5. "Walk me through your first 30 days working with us. What would you do?"

What you're evaluating: Structured onboarding process and ability to identify priorities quickly.

Good answer includes:

• Week 1: Understanding current state (team interviews, technical review, documentation)
• Week 2: Identifying biggest risks and opportunities
• Week 3: Presenting findings and recommendations
• Week 4: Beginning implementation of quick wins

Listen for: Balance between assessment and action. Some fractional CTOs spend months "assessing" without delivering. Good ones deliver quick wins whilst building understanding.

Red flag: No clear plan, just "I'll need to see," or jumping straight to solutions without understanding your situation first.

6. "How do you work with our existing technical team? Will they report to you?"

What you're evaluating: How they integrate with your team without disrupting existing relationships.

Good answer includes:

• Clear reporting structure (fractional CTOs usually work with teams, not manage them directly)
• How they build credibility with existing developers
• Balance between guidance and empowerment
• How they handle disagreements with your team

Standard approach: Fractional CTOs provide strategic direction and architectural guidance. Day-to-day management stays with your Tech Lead or senior developers. They should enhance your team's effectiveness, not create dependency.

Red flag: Wants direct reporting lines (creates conflict), or plans to work around your existing team rather than with them.

Questions about solving your specific problems

7. "Our biggest technical challenge right now is [specific problem]. How would you approach solving this?"

What you're evaluating: Ability to think through your specific challenges and propose sensible approaches.

Good answer includes:

• Questions to understand the problem better (good CTOs don't jump to solutions)
• 2-3 potential approaches with trade-offs
• What they'd need to investigate before recommending a solution
• Estimated timeline and resources required

Example problem: "Our platform goes down twice a week and we don't know why. How would you approach this?"

Good answer: "First, I'd review your monitoring and logging to understand what's failing. Second, I'd check your infrastructure scaling and database performance. Third, I'd review recent code changes. Most intermittent failures are either under-provisioned infrastructure or a recent code change introducing a race condition. I'd have a hypothesis within three days and a solution within two weeks."

Red flag: Jumps straight to a solution without asking questions, or gives vague advice like "implement DevOps best practices."

8. "We're considering [specific technology decision]. What's your opinion on this?"

What you're evaluating: Whether they have informed opinions and can provide decision-making frameworks, not just technical knowledge.

Good answer includes:

• Follow-up questions about your requirements and context
• Pros and cons of the technology
• Alternative approaches to consider
• Framework for making the decision based on your specific needs

Listen for: "It depends on your situation" followed by relevant questions. Beware of anyone who says a technology is always good or always bad.

Example: "We're considering rebuilding our platform in microservices."

Good answer: "What problem are you trying to solve? If it's scaling, microservices can help, but they add significant complexity. For most businesses under £10M, a well-structured monolith is simpler and cheaper. Tell me about your scaling challenges and I can recommend whether microservices make sense."

9. "How would you help us decide whether to build custom or buy off-the-shelf solutions?"

What you're evaluating: Decision-making framework for build-vs-buy, one of the most expensive decisions businesses make.

Good answer includes:

• Framework for evaluating build vs buy
• Questions they'd ask about requirements
• How they calculate total cost of ownership
• Examples of when they've recommended each approach

Listen for: Bias towards buying unless building provides competitive advantage. Most fractional CTOs with business experience recommend buying commodity functionality and building differentiating features.

Red flag: Always recommends building (shows developer mindset, not business thinking) or always recommends buying (might have vendor relationships).

Questions about team and hiring

10. "Our technical team is struggling with [velocity/quality/morale]. How would you diagnose and address this?"

What you're evaluating: Understanding of team dynamics and people issues, not just technical problems.

Good answer includes:

• Questions about team structure, experience levels, and processes
• How they'd assess the actual problem (data, interviews, observation)
• Potential root causes they'd investigate
• How they'd involve the team in solutions

Listen for: Recognition that team problems are rarely just technical. Good fractional CTOs understand that slow delivery might be caused by unclear requirements, not inadequate developers.

Red flag: Jumps to conclusions ("you need to hire better developers") without investigation.

11. "We need to hire a [specific technical role]. How would you help with this?"

What you're evaluating: Ability to help recruit technical talent and assess candidates.

Good answer includes:

• Help defining the role and requirements
• Writing job specifications that attract good candidates
• Technical assessment process
• Evaluating candidates (technical interviews, work samples)
• Making hiring decisions based on business needs

Fractional CTOs typically: Define requirements, assess candidates technically, make recommendations, but don't run the entire recruitment process.

Red flag: Offers to recruit for you (they're strategic advisors, not recruiters) or can't help assess candidates (means they lack hands-on technical depth).

12. "How do you handle situations where our technical team disagrees with your recommendations?"

What you're evaluating: How they build consensus and handle conflict.

Good answer includes:

• Respect for existing team's knowledge and context
• Process for working through disagreements (discussion, data, experimentation)
• Recognition that they might be wrong
• Escalation path for unresolved disagreements

Listen for: Collaborative approach. Good fractional CTOs use disagreement to understand context they might be missing, not to assert authority.

Red flag: "I'm the CTO, they should do what I say" or complete deference to existing team ("whatever they think is best").

Questions about cost and value

13. "What results should we expect in the first 3 months, and how will we measure them?"

What you're evaluating: Clear success criteria and accountability for delivering results.

Good answer includes:

• Specific deliverables (e.g., "technology roadmap aligned with business goals")
• Measurable improvements (e.g., "reduce deployment time from 4 hours to 30 minutes")
• Risk reduction (e.g., "document and mitigate top 3 technical risks")
• Team development (e.g., "establish code review process adopted by team")

Listen for: Mix of quick wins and longer-term improvements. Month 1 should deliver visible value, not just assessment.

Red flag: Only deliverables are documents or assessments with no measurable business impact.

14. "How do you charge, and what's included in your fee?"

What you're evaluating: Clear pricing structure and understanding what you're paying for.

Standard fractional CTO pricing in UK:

• Day rate: £800-1,500/day
• Monthly retainer: £3,000-10,000/month (typically 2-5 days)
• Hourly: £150-400/hour (usually only for ad-hoc advice)

What's typically included:

• Scheduled days/hours
• Limited availability between sessions for urgent questions
• Attendance at specific meetings
• Document review and feedback

What's typically extra:

• Additional days beyond agreed commitment
• Hands-on coding or technical implementation
• Recruitment fees
• Training delivery

Red flag: Unclear pricing, "it depends" without explaining on what, or prices significantly above or below market rate without clear justification.

15. "Can you give me a reference from a similar business you've worked with?"

What you're evaluating: Track record and willingness to have previous clients vouch for them.

Good answer:

• Offers 2-3 references from businesses similar to yours
• Provides context about what they delivered
• Connects you directly (not through carefully curated testimonials)

Follow-up questions to ask references:

• What specific value did they deliver?
• What didn't go well?
• Would you hire them again?
• What type of business would benefit most from working with them?

Red flag: Reluctant to provide references, only offers people they've worked with years ago, or references are from very different business contexts.

Questions about communication and fit

16. "How do you explain technical decisions to non-technical stakeholders?"

What you're evaluating: Communication skills and ability to translate technical complexity into business language.

Good answer includes:

• Examples of explaining complex decisions to boards, investors, or non-technical founders
• Focus on business impact, not technical details
• Use of analogies and clear frameworks
• Written communication samples

Test this in the interview: Ask them to explain a complex technical concept (e.g., microservices, API architecture, technical debt). If you don't understand their explanation, they can't communicate at the level you need.

Red flag: Explains things using jargon and technical terms without translating to business impact.

17. "What questions should I be asking you that I haven't?"

What you're evaluating: Whether they understand what matters in this relationship and can identify gaps in your evaluation.

Good answers might include:

• "Ask about my availability during your peak business periods"
• "You should understand how I handle situations where I can't solve your problem"
• "Check whether my expertise matches your specific technology stack"
• "Ask about my approach to knowledge transfer, you shouldn't become dependent on me"

Listen for: Thoughtful suggestions that help you make a better decision, not softball questions designed to make them look good.

How to use this checklist

Before the interview:

• Send 5-7 of these questions in advance so they can prepare thoughtful answers
• Prioritise questions based on your specific concerns
• Share context about your business so they can give relevant examples

During the interview:

• Ask follow-up questions when answers are vague
• Listen for specifics: numbers, timelines, measurable outcomes
• Watch for red flags: generic advice, no examples, defensive responses
• Evaluate cultural fit: will they work well with your team?

After the interview:

• Check references thoroughly
• Review any written materials or case studies
• Compare candidates on specific criteria, not gut feel
• Trial period: Start with 3-month engagement before longer commitment

What you're actually hiring for

These questions help you evaluate:

Technical expertise: Can they solve your specific technical challenges?

Business understanding: Do they connect technology decisions to business outcomes?

Communication: Can they explain complex topics clearly to non-technical people?

Team fit: Will they work effectively with your existing team?

Value delivery: Do they deliver measurable results, not just advice?

Honesty: Will they tell you what you need to hear, not what you want to hear?

You're not hiring someone to agree with you, you're hiring expertise to make better technical decisions and avoid expensive mistakes.

Red flags that mean "don't hire this person"

Can't provide specific examples of businesses they've helped or outcomes they've delivered.

No relevant experience with businesses at your stage, in your sector, or with your challenges.

Unclear pricing or value proposition without transparent explanation of what you're paying for.

Poor communication when explaining technical concepts to you during the interview.

Defensive about questions or unwilling to provide references.

Only talks about technology without connecting to business outcomes.

Promises transformation rather than specific, measurable improvements.

Making your decision

You've interviewed 2-3 fractional CTO candidates. Now decide based on:

Relevant experience: Have they solved problems like yours for businesses like yours?

Clear value: Do they articulate specific outcomes they'll deliver in first 3 months?

Good communication: Do you understand their explanations and recommendations?

Team fit: Will your technical team respect and work well with them?

Reasonable pricing: Does their fee match the value they'll deliver?

Most importantly: Do you trust them to give you honest advice, even when it's not what you want to hear?

Understand fractional CTO pricing and what you should expect

Book a free 30-minute call to discuss your specific technical challenges and whether fractional CTO services make sense for your business. We'll review your situation and help you determine what questions matter most for your context.

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About the Author

Jake Holmes has worked with 15+ UK businesses (£1-10M revenue) on technology leadership decisions. He's helped companies decide between fractional and full-time CTOs, recruited technical leaders, and prevented £100,000+ in bad hiring decisions. Before founding Grow Fast, Jake was a software engineer and technical lead, giving him the technical depth most consultants lack.

Connect: jake@grow-fast.co.uk | LinkedIn | Book consultation

About Grow Fast

Grow Fast helps UK businesses (£1-10M revenue) make smart technology decisions without wasting money. Our Fractional CTO services provide strategic technical leadership 2-5 days per month, saving you £200,000+ vs hiring full-time whilst getting the expertise you actually need. Book a free 30-minute call to discuss your technical leadership needs.