The 13-Week Cash Flow Forecast Every Owner Should Run

A 30-day forecast doesn't show you the gap that appears in week 9. A 12-month forecast becomes fiction by week 6. Thirteen weeks is the sweet spot where you can plan and still be approximately right.

Start with current cash. Add expected collections by week — use actual AR aging, not optimism. Subtract payroll, rent, vendor payments, debt service, estimated taxes, and owner draws.

Ending balance becomes the next week's starting balance.

Set a minimum operating cash threshold (often 2–4 weeks of payroll). Any week below it gets flagged red. That becomes your action list — collect faster, delay non-critical spend, or tap a line of credit.

The forecast is only useful if it stays current. Friday is a good cadence — the week just finished is fresh, and you still have time to act on next week.

Within a month, patterns show up that no P&L will ever surface: slow-paying clients, the real cost of a new hire, seasonal dips, vendor terms that quietly funded the business.