You’re building a tech startup. You need technical leadership. But you can’t afford a full-time CTO.
Welcome to the club. It’s a crowded one.
The good news: You probably don’t need a full-time CTO. Not yet. What you need is the right technical leadership for your current stage — and that’s exactly what fractional CTOs provide.
But “right for your stage” is the key phrase. Get the timing wrong, and you’ll either waste money or miss critical decisions.
Let me break it down by stage.
Pre-Seed: Do You Even Need a CTO Yet?
Typical situation: You’re a non-technical founder with an idea. Maybe a prototype. Looking for initial funding or building an MVP.
Do you need a fractional CTO? Maybe, but probably not yet.
At pre-seed, the technical decisions are relatively simple:
- What platform should we build on?
- Who should we hire first?
- Is this agency/dev shop any good?
These are important questions, but they don’t require ongoing CTO-level involvement. A few hours of consultation might be enough.
Better options:
- Technical advisor: 2–4 hours per month, £500–£1,500/month. Enough to validate decisions and avoid obvious mistakes.
- CTO-for-hire services: One-time engagements for specific questions (architecture review, vendor evaluation).
- Technical co-founder: If you can find one. Equity alignment creates genuine partnership.
When fractional CTO makes sense at pre-seed:
- You’re building something technically complex (AI, hardware, regulated industry)
- You’re raising significant pre-seed funding and investors want to see technical leadership
- You’ve already hired developers and need someone to manage them
Seed Stage: Architecture Decisions That Haunt You Later
Typical situation: You’ve raised seed funding. Building your first proper product. Team of 2–5 developers. Moving fast.
Do you need a fractional CTO? Often yes.
This is where most startups should consider fractional CTO support. Why? Because the decisions you make now compound.
Choose the wrong tech stack, and you’ll rewrite in 18 months. Hire the wrong first engineers, and you’ll fire them in 6 months. Skip security basics, and you’ll pay for it at Series A due diligence.
A fractional CTO at seed stage typically handles:
- Technical strategy: What are we building, on what platform, in what order?
- Architecture decisions: How will this system scale? What will we regret?
- Hiring guidance: Who do we need? How do we evaluate candidates? What should we pay?
- Developer oversight: Are we building quality code? Are we moving at the right pace?
- Investor translation: Explaining technical progress to non-technical investors.
Typical engagement: 1–2 days per week, £3,000–£6,000/month.
Red flags that scream “you need a fractional CTO”:
- Non-technical founders making technical hiring decisions
- Developers who’ve never scaled a product making architecture decisions
- Agency building your product with no internal technical oversight
- Investors asking technical questions you can’t answer
Series A: Scaling the Team, Not Just the Product
Typical situation: Product-market fit (or close). Scaling revenue. Engineering team growing from 5 to 15+. Processes becoming important.
Do you need a fractional CTO? Probably still yes — but evaluate hiring full-time.
At Series A, the fractional CTO role shifts. Less about technical decisions (your team should handle those now), more about:
- Engineering management: Building processes, culture, and practices that scale
- Technical due diligence: Preparing for Series B investors who will scrutinise your tech
- Hiring at scale: Building interview processes, levelling frameworks, compensation bands
- Vendor management: Evaluating and managing key technical partners
- Technical debt strategy: What do we fix now vs. later?
Typical engagement: 2–3 days per week, £6,000–£10,000/month.
The full-time question: At Series A, you should actively consider hiring a permanent CTO. The decision depends on:
- Complexity: Deep tech or AI companies often need full-time technical leadership sooner
- Funding runway: Can you afford the £150k–£300k+ total cost?
- Equity stage: Is this the right time to bring on a senior equity holder?
- Candidates: Do you have access to the right person?
Many startups find the optimal path is: fractional CTO through Series A, then transition to full-time as Series B approaches.
Series B+: When Fractional Probably Isn’t Enough
Typical situation: Significant scale. 20–50+ engineers. Multiple products or markets. Serious enterprise customers.
Do you need a fractional CTO? Probably not. You need a full-time one.
At this stage, the technical leadership needs are constant:
- Managing a large engineering organisation
- Representing technology at the executive level
- Building and executing multi-year technical strategy
- Handling enterprise customer relationships
- Managing significant technical risk
A fractional CTO can’t do this from 2 days a week. The role requires full-time presence and commitment.
Exception: Some Series B companies use fractional CTOs for specific purposes while also having a full-time CTO or VP Engineering:
- AI/ML specialist advisory
- Security or compliance expertise
- M&A technical due diligence
- Turnaround situations
But these are supplements, not substitutes for full-time leadership.
The Hybrid Model: Fractional CTO + Agency
Common pattern for startups: Fractional CTO provides direction; a development agency provides execution.
How it works:
- Fractional CTO: 1–2 days/week, £3,000–£6,000/month
- Development agency: £10,000–£30,000/month (depending on scope)
- Total: £13,000–£36,000/month for full technical capability
Why it works:
- CTO provides oversight the agency needs
- Agency provides capacity the startup can’t hire
- CTO evaluates agency quality (they often can’t self-assess)
- Clear separation of strategy and execution
Watch out for:
- CTO and agency blaming each other when things go wrong
- Agency bypassing CTO to talk directly to founders
- CTO not having enough time to properly oversee agency work
Make it work:
- Clear decision rights (CTO owns technical decisions)
- Regular three-way check-ins (founders, CTO, agency)
- CTO reviews agency code and architecture regularly
When to Transition to Full-Time
The signals that you’re outgrowing fractional:
1. You need more days than fractional allows.
If you’re at 3–4 days/week, you’re paying fractional rates for near-full-time commitment. At that point, full-time often makes more sense economically.
2. Technical decisions are constant, not periodic.
If every week brings major technical decisions that can’t wait, you need someone there every day.
3. Engineering team exceeds 15–20 people.
Managing this many engineers — hiring, performance, culture, processes — is a full-time job.
4. You’re entering enterprise sales.
Enterprise customers want to meet your CTO. Having a fractional leader can undermine credibility.
5. You’re preparing for major funding rounds.
Series B+ investors scrutinise technical leadership. Full-time CTO signals commitment.
The Handoff: Fractional to Full-Time
When you hire a permanent CTO, the fractional CTO can help with the transition:
- Candidate sourcing: They often know qualified candidates
- Interview process: Helping evaluate technical skills and leadership ability
- Onboarding: Transferring context and relationships
- Advisory: Staying available for occasional guidance
A good fractional CTO wants you to outgrow them. It’s a sign of success.
Some stay on in an advisory capacity — board observer, monthly calls, available for specific situations. Others step back entirely. Discuss the transition plan before you need it.
Decision Framework
Quick assessment:
| Stage | Fractional CTO? | Alternative |
|---|---|---|
| Pre-seed, non-technical founder | Maybe | Technical advisor (2–4 hrs/month) |
| Pre-seed, technical complexity | Yes | — |
| Seed, building first product | Yes | — |
| Series A, scaling team | Yes, but evaluate full-time | — |
| Series B+, 20+ engineers | No | Full-time CTO |
If you’re unsure, talk to a fractional CTO. Most offer initial consultations. They can assess your situation and tell you honestly whether you need them — or whether another option makes more sense.
The good ones will turn down work they’re not right for.
FAQ
How much does a fractional CTO cost for a startup?
UK rates: £800–£1,400/day, or £3,000–£8,000/month on retainer for 1–2 days/week. AI/ML specialists command 25% premium.
Can a fractional CTO help with fundraising?
Yes. They can prepare technical documentation for due diligence, attend investor meetings, and answer technical questions. This is especially valuable for non-technical founders.
What if our fractional CTO wants to become full-time?
It happens. If it’s a good fit, great — you’ve already tested the relationship. Negotiate equity appropriately. If it’s not a fit, be clear about boundaries from the start.
How do we find a good fractional CTO?
Referrals (ask other founders), fractional executive platforms, and LinkedIn. Interview multiple candidates. Check references with previous startups.
What’s the difference between a fractional CTO and a VP Engineering?
CTO = technical strategy, architecture, external representation. VP Engineering = engineering management, delivery, team building. Some fractional CTOs do both; others focus on the CTO side and work alongside a VP Engineering.
Related: Fractional CTO: When to Hire One (And What to Expect)
