How to Build a 13 Week Cash Flow Forecast

A 13 week cash flow forecast projects a company's cash receipts and cash disbursements week by week for the next quarter, so you can see exactly which week you run short. It uses the direct method, meaning it tracks cash actually collected and cash actually paid rather than accrual revenue and expense. That is the whole distinction, and it is the reason the model exists: when liquidity is the problem, recognized revenue tells you nothing useful about whether payroll clears on Friday.

Thirteen weeks is a quarter. The horizon is short on purpose. It is long enough to see a crunch coming and negotiate around it, and short enough that you can forecast individual customer collections and individual vendor payments rather than trends.

When you actually need one

This is a distress tool. Restructurings, turnarounds, a covenant conversation with a lender, a business that has weeks rather than quarters of cushion. Lenders and restructuring advisors ask for it by name, and in a Chapter 11 the DIP lender will usually require one as a condition of funding.

If you are running an ordinary business with a few quarters of runway, you do not need this. You need a monthly cash forecast, and building a weekly one instead means maintaining a level of detail nobody will keep current past the second week.

The line items

Group everything into four blocks. The point of the grouping is that each block answers a different question.

Operating cash receipts. Cash collected from customers, not revenue recognized. If you invoice net 30 and your customers pay in 45 days, the cash from an October invoice lands in the week after Thanksgiving, and that gap is the entire subject of this exercise. Break receipts out by major customer if a handful of them drive the balance.

Operating cash disbursements. Payroll, materials and inventory purchases, rent, marketing, and the rest of operating spend, dated by when money leaves the account. Payroll is usually the largest and most rigid line, so put it on its actual pay dates rather than spreading it evenly.

Non-operating disbursements. Interest, principal amortization, capex, professional fees, anything outside operations. In a restructuring the professional fees line is real money and gets forgotten.

Net cash flow. Receipts less operating disbursements less non-operating disbursements, for each week.

The weekly roll

Under those four blocks sits the part that makes it a forecast rather than a list:

• Cash at the beginning of the week
• Net cash inflow or outflow during the week
• Draws on and repayments of the revolver, DIP facility, or other short-term borrowing
• Cash at the end of the week, which becomes next week's opening balance

Read across that ending-cash row and the answer you came for is sitting in it. The week where it goes negative, or drops under the minimum operating cash the business needs to function, is the week you are planning around.

Reconcile it to EBITDA, or don't trust it

A cash forecast built in isolation drifts from the accrual financials, and once the two disagree nobody believes either one. So the model needs a reconciliation section: start from forecasted EBITDA, then adjust for the balance sheet roll-forwards that separate profit from cash. Accounts receivable, accounts payable, inventory, and accrued payroll are the four that matter.

If the reconciliation doesn't tie, the model is wrong somewhere and you have just found out cheaply. This is the check most 13 week models skip and most of them need.

Those roll-forwards are already built into the balance sheet forecast in the Standard Financial Model and the Runway Tool. Neither is a 13 week model, they run monthly, but the working capital mechanics are the same and the formulas are open if you want to lift them into a weekly grid.

Why not just build a weekly statement of cash flows?

Because a statement of cash flows is an indirect model. It starts at net income and works backward through changes in working capital, which is the right shape for reporting and the wrong shape for managing a crisis. Going directly at cash receipts and cash payments forces you to answer specific questions: which customer pays in week six, which vendor can wait until week eight. The indirect version lets you avoid both.

Keeping it alive

The forecast is only worth the weekly update. Every Monday you replace the prior week's forecast with what actually happened, roll the horizon forward one week, and look at the variance. The variance column is the most useful part of the whole model after the first month, because a forecast that is consistently 15% optimistic on collections tells you more than any single week's projection.