At what stage does a startup need a CFO?

Bring in fractional CFO support at around £1m of annualised revenue, or earlier if you're fundraising or making decisions that keep you awake. Full-time CFO usually waits until £15m to £25m turnover. Very few UK startups need full-time before Series A.

Do we need a full-time CFO to raise a Series A?

Rarely. Most Series A rounds are led with a fractional CFO or a founder plus a strong finance manager. Investors care about the quality of the numbers and the model, not the CFO's employment status. By Series B, some VCs and PE firms do push for a full-time hire.

How much finance support do I need pre-£1m revenue?

A monthly accountant conversation and cloud bookkeeping software (Xero, QuickBooks). Bringing in CFO capability here is usually expensive theatre. Founder time on finance should be 2 to 3 hours a week at this stage.

What are the three moments that trigger an immediate CFO hire?

One: about to raise a funding round. Two: about to sell part of the business or receive an acquisition offer. Three: about to make a decision worth more than a year's CFO fees, such as a big price change, big hire, or major product bet.

Can my accountant do the CFO job?

Sometimes for very small businesses, yes. But most accountants are set up for compliance work (year-end, tax, VAT) rather than forward-looking finance. As soon as you need weekly cash forecasting, board reporting, or a defensible funding model, you need someone whose job is that specifically.

When should a startup hire a CFO?

Most founders wait too long to hire a CFO. The pattern is predictable: the business doubles, cash gets tight, a funding round appears, and the founder spends nights building forecasts in Excel that a CFO would have owned six months earlier.

Here's how to spot the real signals, and what "hire a CFO" actually means at each stage.

The one-line answer

Bring in fractional CFO support when you cross £1m of annualised revenue, when you start fundraising, or when finance decisions start keeping you awake, whichever comes first. Move to full-time somewhere between £15m and £25m turnover.

Almost no UK startup needs a full-time CFO before Series A.

Stage 1: Pre-revenue to £1m ARR

What you need: a good accountant and a bookkeeping process.

What you don't need: a CFO.

At this stage, your finance decisions are simple: track cash, pay bills, file taxes, watch runway. A monthly accountant conversation and cloud bookkeeping software (Xero, QuickBooks) covers it. Bringing in a CFO here is expensive theatre.

Founder time on finance: 2-3 hours a week.

Stage 2: £1m to £5m ARR

What you need: a fractional CFO, 1-2 days a month.

Signals it's time:

You're pricing without a proper margin model.
You're hiring without knowing what it does to runway.
You've raised money and the investor wants a monthly board pack.
Cash flow forecasting has become a founder job you dread.
You've missed a payroll cycle projection or a supplier payment.

A fractional CFO at this stage owns the numbers, sets up management accounts, builds a 13-week cash forecast, and starts sitting in on leadership meetings. Cost: £1,500-£5,000 a month. Full detail on the role in what does an outsourced CFO do?.

Stage 3: £5m to £15m ARR

What you need: fractional CFO, 2-4 days a month, plus a finance manager or controller in-house.

What changes:

You have a real finance team (2-4 people) that needs daily leadership.
Board reporting is monthly, and the questions get sharper.
Cash is bigger but so are the commitments (long leases, senior hires, marketing spend).
Acquisitions, share options, EIS/SEIS unwinds, or overseas expansion appear.

The finance manager handles day-to-day (month-end, AP/AR, payroll). The fractional CFO handles forecasting, board reporting, funding, and commercial decisions. This split works up to about £15m of turnover.

Stage 4: £15m+ ARR

What you need: full-time CFO.

Signals:

Fractional CFO is billing 3.5+ days a month and still short.
Investors or lenders are pushing for a full-timer.
International expansion, complex revenue recognition, or M&A on the roadmap.
Finance team is 4+ people and needs full-time line management.

At this point the £110k-£180k loaded cost of a full-time CFO is money well spent, because they'll pay for themselves in decisions made faster, funding raised on better terms, and mistakes avoided.

Fuller comparison: fractional CFO vs full-time CFO.

The three "hire now" moments

Regardless of revenue, these three moments mean you need CFO capability inside the next 60 days:

You're about to raise a round. You'll want proper forecasts, a defensible model, a data room, and someone who can hold a conversation with an investor's finance team.
You're about to sell part of the business. Whether it's a partial exit, secondary sale, or full acquisition, you need someone who understands normalisation, working capital adjustments, and earn-out mechanics.
You're about to make a decision worth more than a year's CFO fees. Big price change, big hire, big product bet. Get someone to pressure-test it before you commit.

The most expensive mistake

Waiting until cash flow is already a problem. By the time cash is tight, you've lost the ability to negotiate on terms, timing, or investors. A CFO earns their fee twice over just by giving you 90 days of forewarning instead of 30.

Getting started

Calibra CFO is set up for UK startups and SMEs between £1m and £20m turnover. Typical engagements start at 2 days a month and scale up around funding rounds. See Calibra CFO or get in touch for a scoping conversation.