As a SaaS company grows, the question of who leads the finance function becomes unavoidable. Two options come up repeatedly: hire a finance director (FD) or engage a fractional CFO. They sound similar but operate at different levels and solve different problems.
This guide breaks down the differences so you can make the right call for your stage and situation.
What Each Role Actually Does
Finance Director
A finance director is typically a mid-level finance leader who focuses on operational finance and compliance. They work 3 to 5 days per week, manage day-to-day accounting operations, and ensure the books are accurate and compliant. The FD handles management accounts, payroll, tax filings, and financial controls. They report into the CEO or CFO and manage junior finance staff.
Fractional CFO
A fractional CFO is a senior finance leader - often an ex-corporate CFO or qualified accountant with a PE or VC background - who works on an ongoing monthly retainer rather than a fixed number of days per week. The focus is on strategy, financial modelling, investor relations, and board-level thinking. They build the financial narrative, lead fundraising from the finance side, prepare for exits, and make sure every strategic decision has a clear financial framework behind it.
Side-by-Side Comparison
CFO vs Finance Director at a UK SaaS Company: Scope by Domain
The generic comparison above holds in every industry. UK SaaS adds a specific set of domains where the split between fractional CFO and finance director matters more than the job title - SaaS metrics, HMRC schemes (SEIS, EIS, R&D, EMI), board-pack standards UK VCs expect, and the Companies Act 2006 duties that attach to any statutory director. The table below shows who typically owns what at a UK SaaS company between £500K and £5M ARR.
The split is sharper in UK SaaS than in traditional businesses because HMRC schemes and SaaS metrics demand both strategic design AND operational execution. At Seed and pre-Series A stage most companies cannot afford both leads, and the fractional CFO is usually the right first call because UK VCs read the model and the board pack before they read the month-end close. The finance director becomes the right next hire once invoice volume, payroll size, and statutory complexity outgrow what an outsourced accountant can keep clean.
What Each Role Owns, Week to Week
The comparison above is the headline. In practice, the two roles fill very different weeks. Here is what each one typically owns day to day.
Fractional CFO
- The financial model and the three-statement forecast
- Cash flow and runway scenarios for the board and investors
- The board pack narrative and the metrics behind it (ARR, NRR, CAC payback, Rule of 40)
- Fundraising: data room, investor questions, dilution and use-of-proceeds modelling
- Pricing and commercial decisions that need a financial lens
- Capital structure, and preparing the business for a future raise or exit
Finance Director
- Month-end close and the management accounts
- Accounts payable, receivable, and credit control
- Payroll, expenses, and the day-to-day finance team
- Statutory accounts, VAT, and tax filing coordination with the accountant
- Financial controls, approvals, and audit support
- Cash management and supplier relationships on the ground
A fractional CFO sets the financial direction. A finance director runs the machine that keeps the numbers accurate and compliant. Plenty of companies eventually need both, but rarely at the same time, and rarely as the first finance hire.
Board Seats and Statutory Status
There is one difference founders often miss, and it matters more than the job title. Under the Companies Act 2006, a "director" is a specific legal role - someone formally appointed and registered at Companies House - not simply anyone with a senior finance title. Whether your finance lead is a statutory director changes their legal duties, their filing obligations, and their personal exposure.
A fractional CFO is almost always engaged as an adviser or contractor, not appointed to the board. They attend board meetings, present the numbers, and shape financial strategy, but they do not normally take on the statutory duties of a director. For a founder that is an advantage: you get senior financial input in the boardroom without adding another registered director, and without the filing and liability a board appointment carries.
A finance director may or may not be a statutory director. If they are appointed to the board, they take on the seven general duties set out in sections 171 to 177 of the Companies Act - including the duty to promote the success of the company and to exercise reasonable care, skill, and diligence - along with potential personal liability if things go wrong. If they hold the title as a senior employee with no board seat, they carry the operational responsibility without the statutory duties.
One caveat worth knowing: the law looks at conduct, not just paperwork. Someone who acts as a director, or whose instructions the board routinely follows, can be treated as a de facto or shadow director even without a formal appointment. This is general guidance rather than legal advice - if board structure or director liability is a live question, confirm the specifics with your solicitor or company secretary.
What Each Role Costs in the UK
The salary gap is wide, and it tracks the seniority difference. Full benchmarks by company stage and region are in our CFO salary UK guide.
- Finance director (full-time): roughly £90,000 to £140,000 a year in a UK SaaS company, higher in London or at greater scale, plus employer NI, pension, and benefits.
- CFO (full-time): roughly £150,000 to £250,000 base, usually with equity and a bonus on top, plus the cost and risk of a senior recruitment process.
- Fractional CFO: a fixed monthly retainer rather than a salary - no day rates and no recruitment fee. For most early-stage companies it lands at a fraction of a full-time package, which is the whole point of the model.
For a company between roughly £500K and £5M ARR, the fractional route gives you CFO-level thinking without committing to a six-figure hire before the finance workload justifies one.
When to Choose a Fractional CFO
- You are Seed to Series A stage and do not need full-time finance operations yet
- You want CFO-level strategy without a full-time senior hire
- You are preparing for a fundraise or exit and need someone who has done it before
- Your board is asking for financial governance and reporting you cannot currently produce
- Your financial needs will change as you grow - you need flexibility, not a permanent hire
When to Choose a Finance Director
- You are post-Series B with a growing finance team that needs managing
- Day-to-day financial operations are complex enough to require dedicated attention
- You already have a CFO (or fractional CFO) and need someone to execute operationally
- You are planning M&A activity or international expansion that requires full-time finance leadership
Which Role Do You Need at Each Stage?
If you want a simple rule of thumb, map the decision to your stage and revenue.
Pre-seed to ~£500K ARR
A bookkeeper and a good accountant usually cover it. The exception is a fundraise - that is when a fractional CFO earns their fee, building the model and getting the data room investor-ready. No finance director yet.
Seed / ~£500K to £1.5M ARR
This is the fractional CFO sweet spot. You need a credible model, monthly board reporting, and someone who can hold the financial conversation with investors. You do not yet have the transaction volume to justify a full-time finance hire.
Series A / ~£1.5M to £5M ARR
Keep the fractional CFO on strategy and reporting, and add operational capacity underneath - a management accountant or financial controller - as invoicing, payroll, and supplier volume grows. A part-time finance director can make sense here if operations are getting complex.
Series B and beyond / £5M+ ARR
A full-time finance director, or a full-time CFO, starts to pay for itself. The finance function is now a team, and someone needs to run it day to day. This is the natural point to move from fractional to full-time, often with the fractional CFO helping hire and onboard their successor.
The pattern is consistent: strategy first, operations second. Most SaaS founders get more from a fractional CFO than a finance director until the finance team itself needs managing.
Can You Have Both?
Yes - and many growing SaaS companies do. A common pattern is to engage a fractional CFO for strategy, investor relations, and board reporting, while an FD or finance manager handles day-to-day operations, payroll, and compliance. The fractional CFO sets the direction; the FD executes it.
Another common path: start with a fractional CFO at Seed/Series A stage, then hire an FD as operations grow, with the fractional CFO stepping into a lighter advisory role or helping recruit and onboard the permanent finance hire.
Why SaaS Companies Need Specialist Finance Leadership
SaaS finance is fundamentally different from traditional business finance. Revenue recognition follows subscription terms, not invoice dates. Unit economics - CAC, LTV, churn, net revenue retention - matter more than gross margin alone. Investors speak a specific language (ARR bridge, Rule of 40, burn multiple) and expect your finance function to speak it too.
Whether you choose a fractional CFO or a finance director, make sure they have real SaaS experience. Generic finance expertise does not translate to subscription businesses without a steep learning curve.
Summary
A fractional CFO and a finance director are complementary, not competing, roles. The fractional CFO operates at the strategic layer - modelling, investor relations, board reporting, exit planning. The finance director operates at the operational layer - accounting, compliance, controls, team management. Most SaaS companies at Seed to Series A stage get the best value from a fractional CFO first, adding an FD as operational complexity grows.
At ScaleWithCFO, we provide fractional CFO services exclusively for SaaS, AI, and tech companies across the UK. If you are not sure which role you need, book 15 mins and we will help you figure it out.