The Short Answer
What is a fractional CTO?
A fractional CTO is an experienced technology leader who works for a company part-time, typically one or two days a week or on a monthly retainer. They make and review technical decisions, hire and oversee developers or an agency, and represent technology to investors, without the cost of a full-time chief technology officer.
The key word is leadership. A fractional CTO is not usually the person writing most of the code. They are the person who makes sure the code being written, by whoever writes it, is the right code, built the right way, and owned by you.
What a Fractional CTO Does
- Technical strategy. Choosing the architecture and stack, deciding what to build, buy or integrate, and saying no to work that does not serve the plan.
- Overseeing the build. Writing or reviewing the scope, reviewing code and pull requests, and holding a development agency or freelancers to a standard you could not check yourself.
- Hiring. Defining the first engineering roles, running technical interviews and onboarding the first hires.
- Investors and buyers. Answering technical due diligence questions and presenting the technical plan credibly.
- Ownership and risk. Making sure repositories, cloud accounts and IP assignments are in the company's name, and that security basics are in place.
What It Costs in the UK
How much does a fractional CTO cost in the UK?
There is no official dataset for fractional CTOs. The closest benchmark is contract CTO day rates: ITJobsWatch reports a UK median of £630 a day in adverts for the six months to 23 October 2026. At one day a week over 46 weeks, that is about £29,000 a year, roughly a quarter of the cost of a full-time CTO.
Treat the day rate with care. ITJobsWatch counted only 13 unique contract CTO vacancies in the period, and the median was 30% lower than a year earlier, so it moves a lot. Many fractional CTOs also work on a monthly retainer rather than a day rate, and senior people with sector experience charge more.
| Measure | Figure | Sample |
|---|---|---|
| Contract CTO, median day rate | £630 | 13 vacancies |
| Permanent CTO, median salary | £100,000 | 60 salaries quoted |
| Permanent CTO, 10th to 90th percentile | £86,300 to £145,750 | 60 salaries quoted |
For a full-time hire, add employer costs. At the £100,000 median, employer National Insurance at 15% above the £5,000 threshold adds £14,250, and the 3% minimum pension on the £6,240 to £50,270 qualifying earnings band adds about £1,321. That gives roughly £115,600 a year, before recruitment fees, equity and benefits.
Compare the Cost
Interactive calculator
Fractional CTO vs a full-time hire
Day rate times days a week, over 46 working weeks, against a full-time CTO at the UK median salary plus employer costs.
£28,980
Fractional, per year
£115,571
Full-time hire, per year
25%
Fractional as share of full-time
Defaults: ITJobsWatch UK CTO contract median of £630 a day and permanent median of £100,000 (six months to 23 October 2026). Full-time cost adds 15% employer National Insurance above £5,000 and the 3% minimum pension on qualifying earnings, before recruitment fees, equity and benefits. Fractional CTOs often agree a monthly retainer rather than a day rate.
When You Need One, and When You Do Not
| Usually worth it | Usually not worth it |
|---|---|
| You are about to hire your first engineers and cannot assess them | You need someone to write the code; that is a developer or an agency |
| You are managing an agency or freelancers and cannot judge their work | Your agency already provides a named technical lead you trust |
| Investors are about to run technical due diligence | The product is a simple website or a no-code tool |
| You need a technical plan for a fundraise or a rebuild | You already have a technical co-founder |
| Your existing product is unstable and nobody knows why | You have not yet tested whether anyone wants the product |
The last row matters. Before demand is proven, money is usually better spent on the cheapest test that answers the demand question; see MVP examples and MVP vs prototype vs proof of concept.
Fractional CTO vs the Alternatives
| Option | Cost | Best for | Watch out for |
|---|---|---|---|
| Fractional CTO | About a quarter of a full-time CTO at one day a week | Oversight, hiring and strategy | Limited hours; knowledge leaves with them |
| Technical co-founder | Equity, often a large stake | Long-term ownership of technology | Hard to find; costly to get wrong |
| Full-time CTO | ~£115,600 a year at the median, plus equity | A funded company with a team to lead | Too early, they become an expensive developer |
| Agency or studio with a technical lead | Included in a project price | Getting a defined product built | Their lead works for them, not for you |
Many founders combine two: a fixed-price studio builds the MVP, and a fractional CTO reviews the work and prepares for the first hire. Our guides on building without a technical co-founder and freelancer vs agency vs in-house compare the build options.
Making the Arrangement Work
- Agree outcomes, not just days. “Hire two engineers by March” or “pass technical due diligence” is clearer than “one day a week”.
- Put everything in the company's name. Repositories, cloud accounts and domains belong to the company, not to the CTO.
- Get IP assigned in writing. Under the Copyright, Designs and Patents Act 1988, s90(3), an assignment of copyright is not effective unless it is in writing and signed. A consultant's work is not automatically yours.
- Insist on written decisions. Short architecture notes mean the next person, full-time or fractional, inherits the reasoning, not just the code.
- Plan the handover from the start. A good fractional CTO's goal is to hire their own replacement or make themselves unnecessary.
For what comes next, see hiring your first in-house engineer and technical due diligence.
Frequently Asked Questions
What is a fractional CTO?
An experienced technology leader who works for a company part-time, usually one or two days a week or on a retainer, to set technical strategy, oversee developers or an agency, hire engineers and handle investor due diligence.
How much does a fractional CTO cost in the UK?
There is no official dataset for fractional roles. ITJobsWatch reports a UK median of £630 a day in contract CTO adverts for the six months to 23 October 2026, about £29,000 a year at one day a week over 46 weeks. Retainers and senior specialists can cost more.
How much does a full-time CTO cost in the UK?
ITJobsWatch reports a £100,000 median salary in permanent CTO adverts. Employer National Insurance and the minimum pension bring that to about £115,600 a year, before recruitment fees, equity and benefits.
Does a fractional CTO write code?
Sometimes, but it is not the main job. A fractional CTO’s value is in decisions, oversight and hiring. If you mainly need code written, a developer or agency is cheaper.
When should a startup hire a fractional CTO?
When you are managing developers or an agency without the expertise to judge their work, preparing to hire your first engineers, or facing technical due diligence. Before demand is proven, cheaper validation usually comes first.
Do I own the work a fractional CTO produces?
Only if it is assigned to you. Under the Copyright, Designs and Patents Act 1988, s90(3), an assignment must be in writing and signed. Put an IP assignment in the contract.
A fractional CTO is best used to make sure you never need to trust anyone blindly on technology. If that is the problem you have, it is one of the most cost-effective hires a non-technical founder can make.