When to Choose Fractional
Choose a fractional executive when you need strategic expertise without full-time presence. This model works best for:
- Ongoing strategic input: You need continuous C-suite guidance but not daily operational management
- Budget constraints: Your budget doesn't justify a full-time executive salary plus benefits
- Avoiding headcount: You want to avoid permanent headcount commitments
- Pre-Series B stage: You're pre-Series B and need senior expertise part of the week
- Multiple expertise areas: You benefit from someone working across multiple clients, bringing diverse insights
Typical engagement: 1-3 days per week, ongoing basis, 30-day rolling notice period, working across 3-5 clients simultaneously.
When to Choose Interim
- Sudden departure: A C-suite leader has left suddenly and you need full-time cover immediately
- Major transformation: You're in a major transformation requiring daily hands-on leadership
- Specific project: A specific project (ERP rollout, acquisition integration, restructure) needs intensive focus
- Potential to permanent: You want someone who can potentially convert to permanent after proving themselves
Cost Comparison Table
| Role | Fractional (2 days/week) | Interim (5 days/week) | Fractional Saving |
|---|---|---|---|
| CFO | £80k–£150k/year | £240k–£430k/year | ~65% |
| CTO | £90k–£160k/year | £220k–£400k/year | ~62% |
| CMO | £70k–£140k/year | £180k–£350k/year | ~61% |
| COO | £80k–£160k/year | £250k–£450k/year | ~65% |
| CHRO | £70k–£130k/year | £200k–£380k/year | ~64% |
| CISO | £95k–£145k/year | £240k–£360k/year | ~60% |
*Based on typical UK day rates 2026. Fractional calculated at 2 days/week × 48 weeks. Interim calculated at 5 days/week × 48 weeks.
Notice Period Comparison
Fractional: Typically 30 days rolling notice, allowing for flexibility and easy scaling up or down based on business needs.
Interim: Often 1–4 weeks notice period, with some contracts requiring longer notice periods for senior positions or extended engagements.
IR35 Considerations
Both fractional and interim models can operate outside IR35 for medium/large companies, provided the engagement is structured correctly. Key factors include:
- Multiple clients (fractional has advantage here)
- Control over working methods
- Substitution rights
- No mutuality of obligation
For detailed guidance, see our IR35 guide for fractional executives →
The Hybrid Approach
Many companies use a hybrid approach, starting with an interim executive (full-time) during a crisis or transformation, then transitioning to fractional (part-time ongoing) once stability is achieved.
Example journey: Hire interim CFO for 6 months post-acquisition → Transition to fractional CFO 2 days/week for ongoing support → Eventually hire permanent CFO when scale justifies.
Role-by-Role Guidance
Fractional CFO vs Interim CFO
Choose fractional: For ongoing finance leadership, fundraising support, and board reporting.
Choose interim: After sudden CFO departure or during financial restructuring.
Fractional CTO vs Interim CTO
Choose fractional: For ongoing technical strategy and architecture oversight.
Choose interim: During full platform rebuild or tech transformation.
Fractional CHRO vs Interim CHRO
Choose fractional: For steady people strategy and culture development.
Choose interim: During restructure, TUPE, or major redundancy programs.