Rates & sources
UK company rates (Corporation Tax, VAT, payroll NI) as published by HMRC and Companies House.
Source: HMRC — Running a business — figures refreshed at the start of each tax year.
When to use this calculator
- Before pricing a job, setting margin targets, or reviewing hiring costs.
- When you want to test sensitivity around volume, VAT, markup, or overhead changes.
- When you need a practical estimate before committing to a budget or proposal.
- When you are modelling break-even volume and want to see how it shifts as overheads or prices change.
- When you are preparing a quote and need to verify that the margin holds after materials, labour, and VAT are accounted for.
A realistic New Zealand planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Monthly Revenue (£)
6
Cost of Goods Sold (£)
NZ$500
Operating Expenses (£)
5000
Tax Rate (%)
5%
After entering these figures, focus on result first and then rerun the tool with a more cautious assumption to understand the realistic range of outcomes rather than relying on a single estimate.
How to read your results
Result
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator produces a rolling cash flow forecast by taking your opening bank balance, adding projected cash receipts from sales, and deducting cash payments for costs in each period. Enter figures as cash amounts — that is, money you actually expect to receive or pay in the period, not accruals or invoices raised. VAT-registered businesses should include the VAT element in both receipts and payments and show the net VAT settlement as a separate line in the period it falls due.
The model does not incorporate capital expenditure, loan repayments, or tax liabilities unless you add them explicitly. It is a planning tool and will only be as accurate as the assumptions you feed into it. Review and update your forecast monthly against actuals to keep it useful.
Common mistakes
- !Using optimistic assumptions without testing a more cautious scenario as well.
- !Comparing outputs from different tools without checking that the inputs match.
- !Treating the result as a final quote instead of a planning estimate.
- !Forgetting to include employer National Insurance contributions when modelling the true cost of a new hire.
- !Using revenue figures in place of gross profit when calculating margin percentage, which produces a misleadingly high result.
What to do next
- Try at least one more scenario with a lower price or higher cost so you can see the margin floor.
- Use the related calculators below to cross-check VAT, payroll, or break-even figures from another angle.
- Open one of the linked guides if you need more context before you finalise a quote or budget.
- If the margin is tighter than expected, identify which single input has the biggest impact and focus any negotiation there first.
- Keep a record of the assumptions behind this estimate so you can revisit and update it when costs or volumes change.
Frequently asked
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End-of-article next steps
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