What should 13 week cashflows show?

A 13 week cashflow should show the opening cash position, every expected receipt and payment mapped week by week, the resulting closing cash position for each week, the key assumptions driving the numbers, and a variance check against the previous version. The goal is a single view of the next quarter of cash in and out, accurate enough to act on.

What a 13 week cashflow is

A 13 week cashflow is a rolling short term forecast of money coming in and money going out, broken down week by week for the next quarter. It is the standard tool a finance director uses to keep a business in control of its cash. Thirteen weeks is long enough to see a problem coming and short enough to be genuinely accurate. Beyond 13 weeks the numbers become estimates. Inside 13 weeks they should be operational.

It sits alongside the annual budget and the monthly management accounts, but it is a different tool with a different job. The budget tells you where you want to get to. The accounts tell you where you have been. The 13 week cashflow tells you what is about to happen to your bank balance.

The seven things every 13 week cashflow should include

1. Opening cash position

The starting bank balance, reconciled to the actual position this morning. If this number is wrong, everything downstream is wrong. The opening balance should include all bank accounts used for trading cash, less any uncleared payments.

2. Expected receipts, week by week

Every pound you expect to come in, in the week you expect it. This is not sales. It is cash collection. Each receipt is driven by one of four things.

• An existing invoice, with an expected payment date based on terms and on how that customer actually behaves.
• Work in progress, with a forecast invoice date and a forecast payment date.
• Pipeline sales, probability weighted if that helps.
• Other income such as grants, tax rebates or owner loans.

Be honest about the gap between when a customer is supposed to pay and when they actually pay. If a customer has a habit of paying at 45 days, model 45 days, not their stated terms.

3. Expected payments, week by week

Every pound you expect to leave, in the week it falls due. Group these into categories so you can see the pattern.

• Payroll, including PAYE, National Insurance and pension contributions.
• Supplier payments, ideally listed by supplier and at minimum by category.
• VAT, on the correct due date.
• Corporation tax, in the month it falls due.
• Rent, rates and utilities.
• Loan repayments and finance costs.
• Dividends and drawings.
• Capital expenditure.

Missing a category is the most common cause of forecast error. VAT in particular gets forgotten, then lands with full force once a quarter.

4. Closing cash position, for each week

The running bank balance at the end of each week. This is the number that matters, and it should be visible at a glance for every one of the 13 weeks. If it dips below zero, or below your agreed overdraft limit, you need to act. If it dips close to zero, you need a plan.

5. Key assumptions

Every forecast is built on assumptions, and the assumptions belong on the same sheet as the numbers. That means payment terms, collection profiles, pipeline conversion rates, exchange rates where they matter, and any judgement you have made about timing. A forecast without written assumptions is impossible to update and impossible to trust.

6. Variance against last week

A 13 week cashflow is a living document. Each time you update it, compare it against the previous version. Where are the differences? Did a customer pay early or late? Did a payment slip? Did a deal move? Tracking variance every week is what turns a forecast from a spreadsheet exercise into a management tool.

7. Headroom against facilities

If you have an overdraft, an invoice finance line or a loan, the cashflow should show your headroom against those limits as well as against zero. The question is not only whether you run out of cash. It is whether you breach a facility covenant or trip a financial indicator on the way.

What it should look like on the page

The simplest layout works. A row for each line of cash in and cash out, a column for each of the 13 weeks, and a running total at the bottom. Assumptions on a second tab. Variance against last week on a third.

Line	Week 1	Week 2	Week 3
Opening cash	£120,000	£108,500	£114,500
Debtor collections	£48,000	£52,000	...
New sales	£12,000	£15,000	...
Payroll	(£35,000)	0	...
Suppliers	(£28,000)	(£18,000)	...
VAT	0	0	(£24,000)
Closing cash	£108,500	£114,500	...

The columns carry on in the same shape out to week thirteen. The numbers above are illustrative, and the structure matters more than any single figure.

How often to update it

Weekly. A 13 week cashflow updated once a month is too stale to trust by the time you are acting on it. The discipline of updating it every Monday morning against the actual bank position on Friday night is what makes it work. Rolling the forecast forward by one week each time keeps the horizon at 13 weeks.

Red flags to watch for

The forecast is doing its job when it surfaces problems early. Watch for these.

• A dip in the closing cash position four to six weeks out. You still have time to act on it.
• A widening gap between forecast and actual receipts. Either the pipeline is softer than you thought or debtors are paying later. Both need investigating.
• VAT or corporation tax weeks that look tight. HMRC is not a creditor to push on.
• A cluster of discretionary payments landing in the same week. Sometimes moving the timing solves a cash pinch with no operational change at all.

Common mistakes

Treating it as an accounting exercise rather than an operational one. A 13 week cashflow is owned by the person who makes decisions about cash. That is the finance director or the managing director, supported by the finance team.

Forecasting sales rather than receipts. Sales become cash weeks or months later. The cashflow needs the cash date.

Ignoring VAT and tax. These are large, predictable and not negotiable. They should be visible from week one.

Not updating it. A forecast nobody updates is worse than no forecast, because it gives false confidence.

Common questions

Why 13 weeks and not 12 or 26? Thirteen weeks is one quarter. It aligns with VAT cycles, gives a month of solid operational visibility, and is short enough to stay accurate. Twelve weeks misses the quarter end. Twenty six weeks drifts into forecasting rather than management.

Should it replace my annual budget? No. The budget is the annual plan. The 13 week cashflow is a short term cash tool. You need both.

How accurate should it be? Weeks one to four within a few per cent, weeks five to eight within ten per cent, weeks nine to 13 looser because the assumptions stretch further. The point is visibility, not perfection.

Who should own it? The finance director or financial controller, with input from sales on pipeline and operations on cost timing. In a smaller business it usually sits with the managing director, supported by a part time FD or a finance partner.

What software should I use? Excel or Google Sheets by default, because flexibility matters. Tools that pull debtors, creditors and payroll out of Xero or QuickBooks are useful but not essential. Weekly review matters more than the tool.

How we help

We build the 13 week cash view, wire it into your accounting system, update it every week and bring the headlines to the managing director. You keep control of the decisions. It is one of the most useful things a finance function produces and one of the most consistently neglected.