What Should 13 Week Cashflows show?
What should a 13 week cashflow include?
Short answer: A 13 week cashflow should include 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 used by Finance Directors to keep a business in control of its cash position. 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, minus 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 either:
- An existing invoice, with an expected payment date based on terms and customer behaviour.
- Work in progress, with a forecast invoice date and payment date.
- Pipeline sales, probability weighted if needed.
- Other income like grants, tax rebates, or owner loans.
Be honest about the difference 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 is due. Group these into categories so you can see patterns:
- Payroll, including PAYE, National Insurance, and pension contributions.
- Supplier payments, ideally listed by supplier or at least by category.
- VAT, on the correct due date.
- Corporation tax, quarterly or 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 is routinely 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. It should be visible at a glance for every week of the 13. 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. The assumptions need to be written down on the same sheet as the numbers. That includes payment terms, collection profiles, pipeline conversion rates, exchange rates if relevant, and any timing judgements. A forecast without documented assumptions is impossible to update or trust.
6. Variance against last week
A 13 week cashflow is a living document. Each time you update it, compare 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 weekly is what turns a forecast from a spreadsheet exercise into a management tool.
7. Headroom against facilities
If you have an overdraft, invoice finance line, or loan, the cashflow should show your headroom against those limits as well as against zero. The question is not just "do we run out of cash", it is "do we breach a facility covenant or trip a financial indicator along the way".
What a 13 week cashflow should look like
The simplest layout works. Rows for each line of cash in and cash out. Columns for each of the 13 weeks. A running total at the bottom. Assumptions listed on a second tab. Variance to last week on a third.
| Line | Week 1 | Week 2 | Week 3 | ... | Week 13 |
|---|---|---|---|---|---|
| Opening cash | £120,000 | £108,500 | ... | ||
| Receipts | |||||
| Debtor collections | £48,000 | £52,000 | ... | ||
| New sales | £12,000 | £15,000 | ... | ||
| Payments | |||||
| Payroll | (£35,000) | 0 | ... | ||
| Suppliers | (£28,000) | (£18,000) | ... | ||
| VAT | 0 | 0 | (£24,000) | ||
| Closing cash | £108,500 | £114,500 | ... |
Numbers above are illustrative. The structure matters more than any single figure.
How often to update the forecast
Weekly. A 13 week cashflow updated monthly 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:
- A dip in the closing cash position in the next four to six weeks. You have time to act.
- 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 pattern of discretionary payments landing in the same week. Sometimes just timing differently solves a cash pinch without any operational change.
Common mistakes in building a 13 week cashflow
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. The Finance Director or 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, non negotiable payments. They should be visible from week one.
Not updating it. A forecast nobody updates is worse than no forecast because it gives false confidence.
How AI Finance Partners help
We build and maintain 13 week rolling cashflows for SMEs across the South East. We set up the template, integrate it with your accounting system, update it weekly, and bring the headlines to the Managing Director. It is one of the most useful things a finance function can produce and one of the most consistently neglected.
Frequently asked questions
Why 13 weeks and not 12 or 26? Thirteen weeks is one quarter. It aligns with VAT cycles, gives four week operational visibility, and is short enough to be accurate. Twelve weeks misses the quarter end. Twenty six weeks starts to drift into forecasting territory.
Should the 13 week cashflow replace my annual budget? No. They serve different purposes. The budget is your annual financial plan. The 13 week cashflow is a short term cash management tool. You need both.
How accurate should a 13 week cashflow be? Weeks one to four should be accurate within a few percent. Weeks five to eight should be accurate within 10%. Weeks nine to 13 will have more variance because pipeline and timing assumptions stretch further. That is fine. The point is visibility, not perfection.
Who should own the 13 week cashflow in a small business? The Finance Director or Financial Controller if you have one, with input from sales on pipeline and operations on cost timing. In a smaller business, it often sits with the Managing Director supported by a part time FD or outsourced finance partner.
What software should I use? Excel or Google Sheets is the default because flexibility matters. Some cashflow tools plug into Xero or QuickBooks and automate the pull through of debtors, creditors, and payroll. They are useful but not essential. The discipline of weekly review matters more than the tool.
