How to build a 13-week cash flow forecast.

Start with a dated opening balance

Choose the first week of the plan and confirm the cash available at that point. Record the date and source. A balance from last month is not automatically the right starting balance for this week.

The workspace carries opening cash through 13 weekly columns. Closing cash for one week becomes the opening balance for the next. The arithmetic is straightforward: opening cash plus receipts, less payments. The assumptions behind those amounts deserve most of your attention.

Put cash in the week it is expected to move

A sale and a customer payment can happen in different weeks. A supplier invoice and its payment can also fall in different periods. Use expected receipt and payment dates rather than spreading a monthly profit figure evenly across the calendar.

• Receipts: expected customer collections and other cash inflows you can explain.
• Payments: payroll, suppliers, rent, debt payments, taxes and other commitments relevant to the business.
• One-off items: show them in the appropriate week instead of burying them in an average.
• Uncertain amounts: document the assumption and who will confirm it.

Look at the low point as well as the ending balance

A positive balance in week 13 can conceal a difficult week earlier in the plan. Read the weekly path and the lowest projected balance together. Then trace the low point back to the receipts and payments that create it.

The sample workspace is illustrative. Its lowest planned cash is not a target or a benchmark for another business.

Use scenarios to make an assumption discussable

Keep a base plan, then explore the scenario controls in the workspace. A scenario helps you see the arithmetic effect of a changed assumption. It is not a prediction that the change will happen.

When a scenario matters, write down the real-world question behind it: which customer must confirm a date, which cost requires review, or which payment timing needs discussion? Record that work in the action plan with an owner and a due date.

Refresh the plan through weekly review

Record actual receipts and payments for the completed week. Compare them with the plan, explain material differences and update the next weeks using what you have learned.

Keep a consistent weekly rhythm. The goal is a current, reviewable view of the business, with clear responsibility for the assumptions that still need attention. Decisions about obligations, financing or insolvency require the appropriate professional advice.