Home / Methodology
This site uses deterministic formulas based on published GOV.UK and HMRC thresholds for the active tax year.
The calculator uses the active UK tax year and applies either rUK or Scottish income tax bands depending on the selected region.
It estimates income tax attributable to sole trader profit, Class 4 National Insurance on profit above the lower threshold, and optional student loan deductions where selected.
The pension input is treated as a practical cash outflow after tax rather than a full tax-relief engine. That keeps the MVP stable and the take-home number honest for budgeting.
Other income is optional. When you enter it, the site estimates the additional tax interaction between that income and your sole trader profit.
The homepage calculator is the fastest way to turn this guidance into a concrete monthly take-home and tax reserve estimate.
No. It is a planning calculator built for budgeting, comparisons and rough Self Assessment preparation.