Cash Flow Calculator for UK Businesses
Project 12-month UK business cash flow in sterling with HMRC VAT-quarter awareness. Highlights months with negative balances and runway risk.
Cash flow is monthly income minus monthly expenses, tracked as a running balance from opening cash. A 12-month projection plots that running balance month by month and flags any month it goes negative. Most cash crises are visible 3–6 months in advance if you project regularly.
A 12-month UK cash flow forecast tracks monthly cash in (sales, VAT refunds, grants) and cash out (payroll, VAT, PAYE, Corporation Tax, suppliers, rent) to project bank balance. Two UK timing traps catch SMEs: quarterly VAT due one month and seven days after quarter-end, and the 31 January self-assessment payment-on-account.
Cash flow is where profitable UK businesses go to die. You can run a 15% net-margin business into administration in twelve months if customer payment terms are 60 days, suppliers want 30, and you've just hit an £18,000 VAT bill the same week as payroll. P&L solvency and cash solvency are different problems, and this 12-month forecast tool models the cash side.
UK cash flow inputs that catch people off-guard:
- VAT returns — typically quarterly to HMRC, due one calendar month and seven days after the period ends, with electronic payment by direct debit. Plan for a single month's VAT liability as a cash outflow
- PAYE / NI — monthly to HMRC, due 22nd of the following month if paying electronically (19th for cheques)
- Corporation Tax — due 9 months and 1 day after the company's year-end (or quarterly instalments if profits over £1.5M)
- Self-assessment payments on account — for sole traders and personal returns: 31 January (balancing + first instalment) and 31 July (second instalment), each typically half the previous year's tax bill
- VAT registration — mandatory at £90,000 rolling 12-month turnover (2024 threshold). Crossing the line mid-year is a common cash shock if you haven't priced VAT-inclusively
The calculator builds out the next 12 months row-by-row: - Cash in: sales × collection timing (this month, +30 days, +60 days, etc.) - Cash out: payroll, suppliers, rent, software, VAT (every 3 months), PAYE (monthly), Corporation Tax (annually), other - Opening balance → closing balance for each month - Flags: any month where projected closing balance goes negative
For UK SMEs, the British Business Bank's cash flow templates and HMRC's payment deadlines on gov.uk are the authoritative references. If the forecast shows a negative month, the order of remedies is: tighten receivables (invoice day 1, chase day 7, escalate day 21), extend payables, pull forward sales, then financing.
Cash on hand at the start of month 1
12-Month Projection
| Month | Income | Expenses | Net | Balance |
|---|---|---|---|---|
| Jan | $2,500.00 | $12,500.00 | ||
| Feb | $2,500.00 | $15,000.00 | ||
| Mar | $2,500.00 | $17,500.00 | ||
| Apr | $2,500.00 | $20,000.00 | ||
| May | $2,500.00 | $22,500.00 | ||
| Jun | $2,500.00 | $25,000.00 | ||
| Jul | $2,500.00 | $27,500.00 | ||
| Aug | $2,500.00 | $30,000.00 | ||
| Sep | $2,500.00 | $32,500.00 | ||
| Oct | $2,500.00 | $35,000.00 | ||
| Nov | $2,500.00 | $37,500.00 | ||
| Dec | $2,500.00 | $40,000.00 |
Annual Net Cash Flow
Healthy$30,000.00
Positive net cash flow over the year.
Lowest Balance
$10,000.00
Cash stays positive through the projection.
Reached in Month 0
See the formula
See parent calculator at /cash-flow-calculator for the full formula reference.
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Methodology & sources
Rates last verified: May 2026Standard cash-flow projection: running balance = opening cash + cumulative (income − expenses). Inputs are estimates; actual cash flow depends on timing of customer payments and supplier terms.
Rates are reviewed annually or when a region changes its headline rate. If you spot one that's out of date, email [email protected].
For information only. This calculator does not constitute financial, accounting, or tax advice. Consult a qualified professional before making business decisions.