For most early-stage founders, financial management starts simply enough. You keep an eye on cash, handle payroll, and track what’s coming in and going out. Then the business starts moving faster, an investor asks for a detailed financial model, your burn rate becomes harder to explain, and the spreadsheet that worked at seed stage suddenly isn’t cutting it.

That’s the moment most founders start wondering whether they need a CFO – and whether they can justify the cost of one.

The reality is that it depends on where you are and what you’re trying to do. Here’s how to think through it.

What a CFO Actually Does

A CFO is not an accountant and isn’t a bookkeeper. Those functions matter, but they’re about recording and reporting what has already happened. A CFO’s job is forward-looking – helping you understand where the business is headed financially, what decisions will get you there faster, and what risks could derail you along the way.

In practical terms that means owning your financial model and keeping it current, preparing investor-ready forecasts and board packs, managing your cash position and runway, structuring your fundraising rounds, and making sure your compliance obligations – corporation tax, VAT, PAYE, Companies House filings – are handled properly. For UK startups, it also means understanding the incentives that can materially improve your financial position: R&D tax credits, SEIS and EIS advance assurance, EMI option scheme structuring, and grant or innovation funding where it applies.

The shorthand is that a good CFO helps you make better decisions with your money and gives investors the confidence that someone financially credible is steering the numbers.

Six Signs You’re Ready for CFO-Level Support

You’re preparing for a Series A or larger round

Seed investors are often willing to back a founder and a thesis. Series A investors are evaluating a business – which means detailed financial forecasts, clean unit economics, a defensible valuation, and a model that holds up under due diligence. If your current financials aren’t at that level, a CFO gets them there and significantly reduces the risk of a raise stalling on numbers that don’t add up.

Your burn rate is unclear or your runway is shorter than you’d like

If you can’t answer “how many months of runway do we have?” confidently and immediately, that’s a problem – and it’s the kind of problem that compounds quickly. A CFO builds the cash flow visibility that lets you see a problem coming months before it arrives, rather than discovering it when options are already limited.

You’re scaling headcount or operational complexity quickly

Moving from five to twenty people, bringing on enterprise customers, opening a new market – all of these change the financial complexity of the business significantly. Budgeting, forecasting, and cost management that worked at one scale often break at the next. A CFO builds the financial infrastructure that allows the business to grow without the finance function becoming a bottleneck.

You’re expanding internationally or into regulated markets

Cross-border operations introduce transfer pricing considerations, foreign currency exposure, overseas entity structuring, and market-specific regulatory obligations. Getting these wrong is expensive. If you’re moving into a new geography – particularly the US, where the compliance and tax landscape is meaningfully different from the UK – CFO-level input before you set up the structure is significantly cheaper than fixing it afterwards.

You’re navigating an HMRC enquiry, audit, or compliance gap

If your R&D tax credit claims haven’t been reviewed by someone who knows the current HMRC guidance, if your PAYE or VAT position hasn’t been properly reconciled, or if your Companies House filings are overdue, these are signals that financial governance needs attention. A CFO brings structure to compliance as well as strategy.

You’re planning an exit or secondary transaction

Acquirers conduct thorough due diligence, and the state of your financials directly affects both the achievable valuation and how smoothly the process runs. A CFO ensures your records are clean, your metrics are properly documented, and your business is presented in the most credible light when it matters most.

Full-Time CFO or Fractional – What’s Right for Your Stage?

For most startups raising up to Series A, a full-time CFO is difficult to justify on cost grounds alone. A CFO at this level in the UK market typically commands a salary of £120,000 to £180,000 plus equity – a significant commitment for a business that may only need strategic financial input a few days a month.

A fractional CFO provides the same calibre of expertise on a part-time or project basis, at a fraction of the cost. The engagement scales with what you actually need – more intensive around a fundraise, lighter during periods of steady operations. For startups between seed and Series A, this tends to be the most efficient model.

The decision to move to a full-time CFO usually comes at Series B or later, when the volume and complexity of financial decisions warrants dedicated daily leadership – or when a board or lead investor requires it as a condition of the round.

If you’re still managing your finances on spreadsheets and finding it hard to answer investor questions with confidence, you don’t necessarily need to hire a full-time CFO tomorrow. But you do need to get serious about financial strategy – and that usually means bringing in experienced support sooner than feels comfortable.