Understand what this calculator assumes about expenses: it expects profit after allowable expenses. Use this guide to avoid mixing turnover, costs, and personal spending.
Many people track income and costs. This tool does not take a detailed expense breakdown. Instead, it expects you to enter profit after allowable expenses. If you have a bookkeeping summary, the number you want is often labelled net profit (for the tax year you choose).
A full expense questionnaire quickly becomes complex and easy to misunderstand (mixed personal/business use, one-off purchases, special rules). For traffic-first MVP pages, we focus on helping you enter the right high-level inputs and avoid common errors.
- Separate personal and business spending as best you can.
- Use consistent categories so you can explain your numbers later.
- If something feels unclear, do not force it into the calculator; treat the output as a planning estimate and verify official guidance before filing.
Not tax advice. Always verify your final allowable expenses using GOV.UK guidance or an accountant.
Last updated: 2026-04-20
Not on this tool. Compute profit first (income minus allowable expenses), then enter profit.
This tool is a simplified estimator. If capital allowances apply, your final tax position may differ.
Combine them only if that matches how you will report. Otherwise, treat this as an estimate and verify your reporting method.
For official rules and definitions, verify with the references below.