How to build a 13-week cash flow forecast
When cash is tight, monthly forecasts are too coarse: a payroll run and a large customer payment can land in the same month but in different weeks. The 13-week cash flow forecast is the standard tool for seeing those weeks clearly.
1. Work in weeks
The forecast covers the next thirteen weeks, one quarter, at weekly granularity. Timshal supports daily, weekly, monthly, quarterly and yearly models, so the 13-week forecast can be a weekly model of its own beside your monthly plan.
2. Forecast receipts from receivables
Start with open invoices and when customers actually pay them, not when they are due. Add expected new sales with a realistic collection delay. Collections, not revenue, are what fill the bank account.
3. Schedule the payments
- Payroll on its real pay dates, including employer taxes
- Rent, loan payments and other fixed obligations
- Supplier payments from open payables and their terms
- Inventory purchases for product businesses
- Taxes and one-off items such as annual software renewals
4. Draw the minimum cash line
Set the lowest balance you are willing to hold, and watch for the first week the forecast crosses it. That week is when a decision is needed: delay a payment, chase a receivable, draw on a credit line.
5. Roll it forward every week
Each week, replace the oldest forecast week with actuals and add a new week at the end. Comparing what you forecast with what happened is how the forecast gets better.