The Essential Guide to Cash Flow Forecasting

Written by Michael Spyrou | Sep 5, 2025 9:30:00 AM

Cash flow problems are one of the main reasons profitable businesses fail. You can be making a healthy margin on paper, but if you run out of cash at the wrong moment, your business grinds to a halt. I often tell founders that forecasting is like turning the headlights on when you are driving at night. Without it, you are moving fast, but you have no idea what’s coming up on the road.

The truth is, almost every business needs a cash flow forecast. Tim, my co-founder, often says that 99% of companies will require one at some point, unless they are so cash-rich that forecasting adds no value. From my own experience, the companies that embrace forecasting gain confidence to invest, hire, and grow. Those who ignore it often find themselves paralysed by uncertainty.

This guide will take you through what cash flow forecasting is, why it matters, and how to build one that actually works.

What is Cash Flow Forecasting?

At its simplest, a cash flow forecast is a projection of the money coming in and going out of your business over a period of time. It gives you visibility over whether you can pay your bills, invest in growth, or simply keep the lights on.

Many founders confuse a cash flow forecast with a profit and loss statement. They are not the same thing.

  • A P&L shows whether you are profitable.
  • A cash flow forecast shows whether you can survive.

You can have a profitable business on paper, but if you have a long lag between sales and payments, you may still run out of cash. Forecasting makes those gaps visible before they become crises.

Why Every Business Needs It

Tim once told a story about a business with £2 million in revenue and strong profits. On the surface, everything looked great. But the owner was hesitant to invest in staff or even buy a property because he simply did not know what the next 12 months of cash flow would look like. The uncertainty kept him awake at night.

Once we introduced proper financial reporting and built a cash flow forecast, everything changed. He could finally see ahead. He had clarity on when money would come in, what obligations were coming up, and how much room he had to invest. He went from stressed and cautious to confident and decisive.

That is the power of forecasting. It does not create money, but it creates confidence. And with confidence, founders can make better decisions.

From overwhelmed by receipts to confident with clarity: the difference cash flow forecasting can make.

Key Elements of a Good Cash Flow Forecast

So, what makes a cash flow forecast actually useful? In my experience, there are four essential elements:

  1. Payment Cycles
    You need a clear view of when cash is coming in from customers and when payments are going out to suppliers. A gap between the two can create a shortfall even if your P&L looks healthy.
  2. VAT and Tax Commitments
    Quarterly VAT bills often catch businesses off guard. You need to build these into your forecast so they don’t create sudden cash drains.
  3. CapEx and One-Off Costs
    Large capital expenditures or investments in new products can distort cash flow if they are not anticipated. Forecasting ensures you know whether you can afford them.
  4. Working Capital Efficiency
    Good credit control, sensible stock management, and efficient invoicing all contribute to smoother cash flow. These are operational levers that a Financial Controller can manage day-to-day.

How to Build One That Actually Works

A lot of founders I meet have some form of spreadsheet they built themselves. That is a start, but it rarely captures the full picture. A proper forecast should follow these steps:

  1. Gather All Inflows and Outflows
    List every expected source of income and every outgoing cost. Be thorough. Missing even small items can distort the forecast.
  2. Include Seasonal and One-Off Items
    Factor in peaks and troughs. For example, a retail business should model Christmas spikes and quieter summer months.
  3. Model Different Scenarios
    Don’t just build one forecast. Create three: best case, expected case, and worst case. This gives you room to stress-test your plans.
  4. Update Regularly
    A forecast is not a one-off exercise. It should be updated monthly with actual results, so it becomes a living tool rather than a static document.
  5. Leverage the Right RolesIn our model, the Financial Controller ensures the numbers are accurate and up to date. The CFO then interprets those numbers and uses them to shape strategy. That separation of duties is key.

Common Mistakes to Avoid

  • Confusing profit with cash flow – they are not the same.
  • Over-optimistic assumptions – assuming every client will pay on time is risky.
  • Treating forecasting as a one-off – it should be dynamic, not static.
  • Putting it all on the CFO – controllers build the numbers, CFOs make the strategic calls.

The Bottom Line

Cash flow forecasting is not a “nice to have.” It is the foundation for confident decision-making. It is what lets you invest in growth, hire the right people, and sleep at night knowing you will not run out of money unexpectedly.

As I often tell founders, profitable businesses don’t fail because of poor margins. They fail because they run out of cash. A forecast is the simplest, most effective way to prevent that from happening.

At Axcelera, we help businesses put the right layers in place: bookkeepers to keep the numbers moving, controllers to build the forecasts, and CFOs to turn them into strategy. That way, you get the clarity you need, without paying a CFO to update spreadsheets.

Axcelera delivers a full-stack finance function through four service areas.
Each layer works together to provide businesses with tailored financial expertise at every stage of growth.

 

 

Learn From Other Founders

Want to see how other scale-ups are handling these challenges?

Watch our recent podcast episode, SMEs: From Chaos to Clarity, featuring Rupert Lee-Browne (CEO of Caxton) alongside Axcelera Co-Founders Michael and Tim.

watch it on LinkedIn

 

 

FAQs

Q: What does a Fractional CFO do?

A Fractional CFO brings commercial insight without the full-time cost. They step in to guide strategy, build forecasts, and support fundraising, so founders can focus on growth.

Q: How much does a Fractional CFO cost in the UK?

A full-time CFO in London can cost over £150,000 per year. A Fractional CFO service is typically 40–60% less, with flexible day rates that start from a few hundred pounds, depending on the level of support you need.

Q: What is the difference between a CFO and a Financial Controller?

A CFO focuses on strategy, growth, and investor relations. A Financial Controller ensures reporting and processes are accurate, so the CFO has the right data to make decisions.

Q: Why do businesses choose Fractional CFO services instead of hiring full-time?

Every ambitious business will eventually need a CFO, but not all the time. A Fractional CFO gives you flexibility, cost efficiency, and senior expertise exactly when you need it—without paying for capacity you don’t.

Q: How do I know if my startup needs one?

If you are preparing for fundraising, expanding internationally, or struggling to get visibility on cash flow, a Fractional CFO is often the right choice. Take our free two-minute Fractional Finance Assessment to see whether your business needs a CFO, Controller, or Bookkeeper right now.

 

 

Let's work together...

A fractional CFO is not just a financial manager. They are a strategic partner who helps you unlock funding, build better forecasts, and achieve financial clarity.

For London-based tech founders aiming for sustainable scale, this is the smartest move to grow stronger, faster, and with confidence.

If you're curious about what a part-time flexible CFO in London or full-stack finance team of experts could bring to your business, don't wait any longer,  do our assessment or book a meeting with us to explore your options.