The 13-week cash flow forecast: How to see problems before they hit

Large companies and investment groups share one habit. They make no decisions about short-term liquidity without an up-to-date cash flow forecast for the next 13 weeks. Not the annual budget. Not the monthly P&L. A weekly rolling forecast that moves one week forward each week.

In mid-sized companies with revenues of CZK 25 to 250 million (roughly EUR 1 to 10 million), this tool is typically missing. Decisions about payments, investments, and bank negotiations are made on the owner's intuition. That works as long as the company grows slowly and predictably. As size, seasonality, and the number of supplier relationships increase, however, intuition becomes a progressively weaker tool. The risk of insufficient cash in any given week grows and only becomes visible when it is already too late.

At numericky.cz, we deploy this tool specifically for this size segment. The objective: detect a potential liquidity crisis early enough to prevent it.

Liquidity vs. profit: two different questions

The P&L answers: are we profitable? The 13-week cash flow forecast answers: will we have money in the bank to pay what must be paid in the week it is due?¹ Accounting works on an accrual basis (when an expense or revenue arises), while the 13-week forecast uses what is known as the direct method: it forecasts actual receipts and disbursements in the bank account, week by week. The aim is not to forecast earnings but to forecast cash.²

You can post an accounting profit and still run out of cash, because customers pay late, inventory peaks seasonally, or VAT lands in the same week as a major supplier invoice. The P&L will not show you that week. The forecast will.

How a 13-week forecast saved a company from a payment crisis

A manufacturing company, revenues of CZK 280 million. In January 2026, the annual budget looked healthy: projected EBIT of CZK 14 million, cash flow positive throughout the year.

In early February 2026, we built a 13-week forecast covering the period from 2 February to 3 May. In week 11, the period from 13 to 19 April, cash flow was projected to drop into negative territory by CZK 8.5 million. We are writing this article in that very week, so we can confirm with certainty: the crisis did not happen.

The reason for the original projected shortfall: seasonal inventory build-up coincided with a major supplier payment, all in the same week, with no offsetting receivables. Customers were paying on 65-day terms.

The annual budget could not show this. The monthly P&L could not show it either. The forecast did, eleven weeks ahead.

That gave the company ten weeks to take concrete action:

→ Renegotiate payment terms with the main supplier, adding 15 days.
→ Launch targeted collections on the three slowest-paying key customers.
→ Proactively inform the bank and secure a temporary overdraft increase on standard terms.

Without the forecast, the company would have spotted the problem 2 to 3 weeks ahead. The bank would have had no time to react. The supplier would have had no incentive to concede.

Why exactly 13 weeks and weekly granularity

The 13-week cash flow forecast (commonly TWCF) originates in the restructuring practice of major advisory firms. KPMG's crisis cash flow methodology states the requirement directly: a rolling 13-week short-term cash flow in receipts-and-payments format, updated at least weekly, reconciled to the actual bank balance.³ Banks demand this output to assess covenant breach risk and debt service capacity. Private equity investors use it to gauge whether management maintains short-term liquidity discipline.⁴

Why 13 weeks: a shorter horizon (under 8 weeks) shows only operational noise. A longer one (over 20 weeks) loses precision. 13 weeks covers one quarter and provides visibility to the next reporting milestone, far enough to react, close enough for realistic numbers.

Why weekly granularity: the monthly view is inadequate for liquidity for the same reason that an average citywide temperature is inadequate when you are deciding whether to wear a coat. A company can end a month CZK 2 million in the black and still spend one specific week CZK 1.5 million in the red, because VAT, payroll, and a major invoice all fall due that week. Weekly granularity exposes the exact week when cash runs short. Monthly reporting hides it.

A living tool, not a document in a drawer

The forecast moves one week forward each week and is reconciled with reality each week. On Monday 20 April 2026, you look at weeks 1 to 13 (the period 20 April to 19 July). One week later, you look at weeks 2 to 14 (27 April to 26 July). Always 13 weeks ahead.

Three steps every week: reconcile the opening balance with the actual bank account, update expected collections and the payment calendar, calculate the variance between actuals and last week's forecast and identify the causes.³ After 4 to 6 cycles, you have a tool you can trust.

What to do when the forecast shows a shortfall

The standard sequence of actions, as recommended by KPMG and Deloitte: first protect mandatory payments (payroll, critical suppliers), then operational levers (accelerate collections, slow non-critical disbursements, pause CAPEX), and only then financial backstops (overdraft, factoring).⁵ The key principle: the earlier you have the forecast, the more steps from this list you can afford. Without the forecast, only the last item remains, and in a crisis you negotiate it from the weakest position.

How it works for our clients

At numericky.cz we connect the forecast to your bank, pulling transactions via API every day. From the bank statements, we continuously monitor and categorise payments and use them to build an up-to-date cash flow forecast. Planned outflows such as payroll, VAT or loan payments are entered once and the system allocates them to the correct weeks automatically.

On Monday morning, the client has an updated 13-week forecast with no manual input. If a critical week is approaching, the client receives notice in time, including proposed concrete actions.