A business can be profitable on paper and still struggle to make payroll. Profit tells you whether the work makes money over time. Cash tells you whether you can pay everyone this Friday. The gap between the two is where many small businesses get into trouble, especially at the end of the year, when customers pay more slowly and bills keep arriving on schedule.
A 13-week cash flow forecast is one of the simplest ways to close that gap. Thirteen weeks is one quarter: long enough to see a problem coming, short enough to plan week by week with real numbers. It is a format lenders and turnaround advisers often work with, and it needs nothing more than a spreadsheet and about an hour to set up.
What a 13-week cash flow forecast is
It is a table with 13 weekly columns and four main rows:
- Opening cash: what is in the bank at the start of the week.
- Cash in: money you expect to actually receive that week.
- Cash out: money you expect to actually pay that week.
- Closing cash: opening cash plus cash in minus cash out. It becomes next week’s opening cash.
The key rule is to record cash in the week it actually moves, not the week you send an invoice or receive a bill. An invoice you send today on 30-day terms is not cash this week. It belongs in the week the customer is likely to pay.
Step 1: Start with the cash you actually have
Use your real bank balances as of today, across every operating account. Leave out money that is not yours to spend, such as sales tax you have collected and still owe. Treat a line of credit as a safety net you can draw on, not as cash in the bank.
Step 2: List the cash coming in
Go through your open invoices and place each one in the week that customer realistically pays, based on how they have paid in the past rather than the due date printed on the invoice. Then add sales that are booked or close to certain, such as signed contracts, deposits and recurring retainers. Leave out hopeful pipeline.
If you are unsure about a receipt, move it one week later. A forecast that is a little cautious about cash coming in is far more useful than one that is optimistic.
Step 3: List the cash going out
Start with the payments that have fixed dates and amounts, then work toward the ones that vary:
- Fixed and dated: payroll and payroll taxes, rent, loan payments, insurance and software subscriptions.
- Taxes: sales tax remittances and any estimated income tax payments. Many owners who pay estimated tax have a fourth-quarter payment due in mid-January, so confirm your dates with your accountant.
- Variable: supplier bills, materials, contractors and shipping.
- Irregular: annual renewals, equipment, year-end bonuses, and any weeks when you close for the holidays but still pay staff.
Irregular items are the ones that cause surprises. Look back at last year’s bank statements for November through February to catch anything that only comes around once a year.
Step 4: Find the low point and decide now
Once the table is filled in, look along the closing cash row and find the lowest week. Compare it with a minimum balance you are comfortable holding, for example enough to cover one payroll plus rent. If any week falls below that line, you still have time to act:
- Invoice promptly when work is done, and follow up on overdue invoices before the holidays.
- Ask for deposits on new work.
- Delay purchases that are not urgent.
- Talk to key suppliers about timing early, rather than paying late without warning.
- Arrange or review a line of credit while your numbers still look healthy, not in the week you need it.
The point is not to predict the future perfectly. It is to see the tight week while there are still several weeks left to do something about it.
Step 5: Update it every week in 30 minutes
A forecast you build once and then ignore stops being useful within a month. Pick the same time each week, such as Monday morning, and:
- Replace last week’s forecast with what actually happened.
- Add a new week at the end, so you always look 13 weeks ahead.
- Note where forecast and actual were far apart, and why.
- Name one person who owns the update.
Writing these steps down as a short routine makes the task easy to hand off. Our guide on how to write a standard operating procedure shows how to turn a weekly task like this into a simple checklist anyone on your team can follow.
Why start now: the year-end gap
November through January is a demanding stretch for cash. Holidays slow down customer payments and approvals, while annual renewals, year-end bonuses and early-year tax payments arrive on their usual dates. A forecast you start this week runs to early February, which covers that whole period.
If the forecast shows you may need outside funding, it also makes that conversation easier. Many small firms seek financing to cover everyday operating costs, as we discussed in our look at lessons from the latest small business credit survey. A clear 13-week view shows a lender exactly what you need, when you need it and how you plan to repay it.
Key takeaways
- Track cash in the week it actually moves, not when you invoice or get billed.
- Place each receipt in the week the customer realistically pays.
- Set a minimum balance and look for your lowest week first.
- Update the forecast every week and roll it forward so you always see 13 weeks ahead.
- Start before the holidays so the forecast covers the slow-payment months.
Want help setting up your cash routines?
CNM Business Consulting helps small and mid-sized businesses improve operations, standardize processes and keep costs under control. If you would like help setting up a weekly cash routine that fits how your business runs, explore our management consulting services or book a free 30-minute consultation.
