Cash-flow forecasting that helps a business make decisions

A cash-flow forecast is useful only when it predicts when money actually reaches or leaves the bank. It should show the point at which the company may run short early enough to change the plan, collect cash faster or arrange funding before the problem becomes urgent.

Choose a forecast period that covers the full cash cycle

The British Business Bank recommends forecasting for at least as long as the business cash-flow cycle. For many small companies, a rolling 13-week forecast is practical because it is detailed enough for weekly decisions while still showing the next quarter. A seasonal company may also need a twelve-month view to see stock purchases, tax dates and quieter trading periods that fall outside the next 13 weeks.

Start with the opening bank balance and one column for each week. Add the cash expected to arrive and subtract the cash expected to leave. The resulting closing balance becomes the next week's opening balance. Do not build false precision six months ahead. The further out the forecast goes, the more assumptions it contains. Use weekly detail near term and broader monthly estimates further out if that better reflects what the business actually knows.

Forecast cash when customers are likely to pay, not when invoices are raised

A profitable month can still create a cash shortage if customers have not paid yet. The British Business Bank specifically distinguishes cash flow from profit and recommends recording income when cash is expected to reach the business. Use actual customer behaviour where possible. If a customer regularly pays 15 days late, forecasting the contractual due date will overstate available cash.

For example, suppose a company raises £60,000 of invoices in November on 30-day terms. If historic payment behaviour shows that £20,000 usually arrives within 30 days, £30,000 arrives during the following two weeks and £10,000 takes longer, the December cash forecast should reflect that pattern rather than placing the full £60,000 on one date. The same logic applies to card settlements, marketplace payouts and grants.

Map the dates money must leave, including tax and irregular costs

List payroll, PAYE, VAT, rent, loan payments, supplier invoices, insurance, software renewals, inventory, professional fees and planned capital spending. Use the date the payment is expected to clear rather than spreading annual costs evenly unless that is how the cash genuinely leaves. A £24,000 annual insurance renewal due in one week is a very different cash event from £2,000 paid monthly.

Add a separate line for tax. Corporation Tax, VAT and Self Assessment can create large cash outflows that do not align with the month in which profit was earned. Keep the expected payment dates visible inside the forecast rather than relying on memory. This is one reason an apparently healthy bank balance should not automatically be treated as spendable surplus.

Build a downside case before cash becomes tight

A forecast should answer "what if?" as well as "what do we expect?". Create a base case and at least one downside case. Useful stresses include sales 15 percent lower, the largest customer paying 30 days late, a key supplier requiring faster payment, or a major repair occurring unexpectedly. The purpose is not to predict disaster. It is to identify how much buffer the company has before a normal setback becomes a funding problem.

Imagine the base forecast shows a lowest cash balance of £42,000. If a £35,000 customer payment moves four weeks later, the lowest balance falls to £7,000 while payroll of £18,000 is due the same week. That tells management something actionable. It may be time to chase the debtor earlier, delay discretionary spending, agree supplier terms or arrange working-capital finance before the gap appears.

Track the operating drivers behind the bank balance

The British Business Bank highlights debtor days, inventory days and supplier days as useful indicators alongside cash on hand and sales. These numbers explain why the bank balance changes. Rising sales can actually increase cash pressure if the business must buy stock and pay staff before customers pay. Growth is not automatically a cash-flow cure.

Choose two or three drivers that matter to the business. A wholesaler might track debtor days, stock days and creditor days. A service company may care more about work in progress, customer payment timing and payroll. When the forecast deteriorates, the driver tells the team where to act. A falling bank balance is the symptom; slow collection or excess stock may be the cause.

Turn the forecast into a short weekly management routine

Update actual cash movements against the forecast every week. Move unpaid customer receipts to their new expected dates, add new commitments and remove assumptions that are no longer realistic. Compare the previous forecast with what actually happened. Repeated forecast errors are useful information because they show where assumptions are weak.

Finish the review with three numbers: current available cash, lowest forecast balance and the date of that low point. Then record the action needed, if any. A forecast that sits in a spreadsheet and is never discussed is a reporting exercise. A forecast that triggers earlier debt collection, slower discretionary spending or a finance discussion is a management tool.