A 13-week cash flow forecast in one afternoon

admin — Tue, 21 Jul 2026 09:00:00 +0000

Plenty of profitable businesses run out of cash. The problem is usually timing: customers pay late, a tax bill lands in the same week as payroll, or stock has to be paid for before it’s sold. A rolling 13-week forecast shows those pinch points while there is still time to act.

Set it up

Open a spreadsheet with 13 columns, one for each week.
Start with today’s bank balance.
List money coming in, in the week you expect it to arrive — not the week you invoice.
List money going out: wages, rent, suppliers, loan repayments, subscriptions and tax.
Work out the closing balance for each week. It becomes next week’s opening balance.

Don’t forget the tax dates

PAYE and National Insurance: by the 22nd of each month if you pay electronically.
VAT: one month and seven days after the end of each VAT quarter.
Corporation Tax: nine months and one day after the company’s year end for most small companies.
Self Assessment: 31 January and 31 July for payments on account.

Read the results

Look for weeks where the balance dips low or turns negative. That is your early warning. Common fixes include chasing overdue invoices, agreeing shorter payment terms with customers, spacing out supplier payments, or asking HMRC about a Time to Pay arrangement before a deadline, not after it.

Keep it rolling

Update the forecast every week: replace estimates with actual figures and add a new week at the end. Ten minutes a week is usually enough once the structure exists.

How we help

We build your first forecast from your bookkeeping data, connect it to your tax calendar and review it with you monthly — so cash decisions are made with numbers, not nerves.