The 13-week cash flow forecast, explained for owner-run companies
Why lenders and advisors rely on a 13-week cash forecast, and how to build one that stays accurate.
Profit tells you whether the business works. Cash tells you whether it gets through the next quarter. The 13-week cash flow forecast is the tool finance leaders use to see the next three months of cash week by week, and it's one of the first things a lender, investor, or interim CFO will ask for when things get tight.
Why 13 weeks
Thirteen weeks is one quarter. It's long enough to see payroll cycles, rent, debt payments, and seasonal swings, and short enough to forecast with real detail rather than broad assumptions.
Build it from the bank account
Unlike a budget, a 13-week forecast starts with actual cash: this week's opening bank balance. From there, each week lists expected receipts and disbursements:
- Customer collections, based on open receivables and typical payment timing
- Payroll and payroll taxes on their actual dates
- Rent, debt service, insurance, and other fixed payments
- Vendor payments from open payables and planned purchases
- One-time items like capital spending or tax payments
Compare forecast to actual every week
The forecast earns trust through a weekly routine. Each week, the prior week's forecast is compared with what actually happened, the differences are explained, and a new week is added at the end. After a month of this, leadership knows how far to trust the numbers.
What it tells you
A good 13-week forecast shows the lowest cash point in the quarter and when it hits. That gives you time to act: delay a purchase, push collections, draw on a line of credit, or talk to the bank early, which is always a better conversation than talking to them late.
When to build one
You don't need a crisis. Companies with seasonal swings, fast growth, a covenant to watch, or an active lender relationship benefit from a 13-week view all the time. It takes a few days to build properly and an hour or two a week to maintain.