Cash Flow · 2026-07-20 · 9 min read

Written and reviewed by Project Financial Advisor · FCA · CGMA · ACMA — Chartered Accountant

Cash Forecasting Methods: Direct, Indirect, 13-Week & Driver-Based

Cash forecasting methods fall into two families. Direct methods build the forecast from actual expected receipts and payments, dated line by line. Indirect methods derive cash from the profit forecast, adjusting for non-cash items and working-capital movement. Everything else you will meet in practice, from the 13-week model used in turnarounds to the driver-based forecasts behind multi-year models, is a variation on one of those two ideas. This guide explains each method, what it is good at, where it breaks down, and how to pick the right one for your situation.

The four methods at a glance

The direct method: forecast the actual money

The direct method lists every expected cash receipt and cash payment in the period it will actually hit the bank. Customer collections are timed from invoice date plus payment terms. Payments are scheduled from payroll dates, supplier due dates, rent, tax instalments and debt service. Net the two and you have the cash movement for each day or week.

Its strength is precision. For the next four to six weeks, a well-kept direct forecast is accurate enough to manage payments against, because it is built from real invoices rather than assumptions. Its weakness is reach: beyond a few months you no longer know which invoices will exist, so the forecast degrades into guesswork dressed as detail. Maintaining it is also real work, which is why the direct method usually lives in treasury or the finance team's weekly routine rather than in a board pack.

The 13-week cash flow forecast

The 13-week forecast is the direct method run weekly across one quarter, and it has become the standard liquidity tool in turnarounds and any tight-cash situation. Thirteen weeks is long enough to act on a projected shortfall and short enough that weekly numbers stay credible. Each week you drop the completed week, add a new week 13, and compare actuals against forecast so the assumptions keep learning. A business that spots a $40,000 gap in week 8 has seven weeks to collect faster, delay a payment or draw a facility. One that finds it in week 8 has a crisis.

The indirect method: derive cash from profit

The indirect method starts from forecast net income, adds back non-cash charges such as depreciation, and adjusts for movements in working capital, CAPEX, debt and tax. It is the method behind the cash flow statement in every three-statement financial model, which is exactly why planners use it: cash, profit and the balance sheet stay linked, and a change to any assumption flows through all three.

The indirect method answers a different question than the direct method. It will not tell you whether Thursday's payroll clears. It will tell you whether next year's plan funds itself, how much financing a growth plan needs, and what the bank covenant looks like in month 18. For any horizon past a quarter, this is the method that scales.

Driver-based forecasting: working-capital days do the timing

Driver-based forecasting is the indirect method with the timing made explicit. Instead of guessing the working-capital movement, you set three drivers: receivable days (DSO), inventory days (DIO) and payable days (DPO). The model converts profit into cash period by period from those settings. A business with 60-day collections and 30-day supplier terms consumes cash as it grows, and the model shows precisely how much and when.

The chart makes the point better than any definition: two forecasts with the same profit and different collection terms produce completely different cash curves. The 60-day version dips toward its funding limit in month 4 while the 30-day version never comes close. This is why lenders read the working-capital assumptions before they read the revenue line.

Rolling forecasts beat static ones

Whichever method you choose, a forecast with a fixed end date goes stale. A rolling forecast keeps the horizon constant: each closed month or week adds a new one at the far end, and actuals replace estimates as they land. The refresh discipline matters more than the format. Persistent gaps between forecast and actual are information, and they almost always point at one assumption, most often collection timing, that can be fixed once and improve every future period.

Where each method goes wrong

Direct forecasts fail through optimism about collections; assuming every customer pays on the due date overstates near-term cash in nearly every real business. Indirect forecasts fail by ignoring seasonality, letting an annual average hide a mid-year trough that a monthly view would have exposed. Driver-based forecasts fail when the days assumptions are copied from an industry table instead of computed from your own ledger. And every method fails when tax instalments and debt repayments are left out, because those two outflows are real, dated and non-negotiable.

From method to model

A cash forecasting spreadsheet built by hand can implement any of these methods, but the linking is where errors live: the working-capital schedule must tie to revenue, the cash flow to the P&L, and the closing balance to the balance sheet. The EasyFinancialModels Cashflow Forecasting tool builds the driver-based method as a self-balancing Excel workbook — monthly, quarterly or annual, with DSO, DIO and DPO driving the timing, a dedicated working-capital schedule and the peak funding need on the dashboard. It is free for a 3-year forecast, no sign-up. For the weekly discipline, pair it with the 13-week approach described in our dedicated guide, and read the working-capital days guide to set the drivers from your own numbers.

Frequently asked questions

What are the main cash forecasting methods?

Four dominate in practice: the direct method, which lists expected receipts and payments by date; the indirect method, which starts from net income and adjusts for non-cash items and working capital; the 13-week forecast, a weekly direct-method view of the next quarter; and driver-based forecasting, which converts revenue and cost assumptions into cash using working-capital days.

Is the direct or indirect method more accurate?

Over short horizons the direct method wins, because it works from real invoices and due dates. Beyond about three months its accuracy decays fast, and the indirect method becomes more practical since it links to the forecast P&L and balance sheet. Most finance teams run both: direct for the near term, indirect for the plan.

Which cash forecasting method should a startup use?

A driver-based monthly forecast. Startups rarely have enough invoice history for a pure direct method, but they do have assumptions: pricing, growth, payment terms. Driver-based forecasting turns those into monthly cash movement and shows the runway, which is the number founders and investors actually watch.

How often should a cash forecast be updated?

Weekly if cash is tight, monthly otherwise. A forecast is only as good as its last refresh: compare actuals against forecast, then fix the assumption that drifted rather than the output. When collections keep coming in slower than forecast, the receivable-days assumption is wrong, and correcting it improves every future period at once.

→ Build your cash flow forecasting model free with the Cashflow Forecasting tool

More Cash Flow Forecasting guides

How to Build a Cash Flow Forecast in Excel (Free Template + Steps) · 13-Week Cash Flow Forecast: A Practical Guide for Tight Cash · Direct vs Indirect Cash Flow Forecasting: Which Method to Use · Cash Flow Forecasting for Startups: Runway, Burn Rate & When to Raise · Working Capital Days Explained: DSO, DIO & DPO and Why They Drive Cash

About the author

Every model is built and reviewed by the project's Financial Advisor — a Fellow Chartered Accountant (FCA), Chartered Global Management Accountant (CGMA) and Associate Chartered Management Accountant (ACMA) with around two decades of corporate finance, audit and accounting experience, designing investor-grade financial models across industries. Full credentials and background are available on LinkedIn. More about the author →

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