§ Methodology
Every calculation, openly documented.
This page documents every assumption and rate used by our calculators for the 2026/27 tax year (rules in force from 6 April 2026). Calculations are deterministic and the engine source is structured so each rate change is a single-file update.
Verified
§ 01
Income tax — England, Wales & Northern Ireland
- Personal Allowance: £12,570 (frozen until 2030/31)
- PA taper: reduces £1 for every £2 above £100,000 adjusted net income; reaches zero at £125,140
- Basic rate 20% on taxable income up to £37,700
- Higher rate 40% on taxable income £37,701 — £112,570
- Additional rate 45% above £112,570 taxable
§ 02
National Insurance
- Employee Class 1: 8% on earnings £12,571 — £50,270; 2% above
- Employer Class 1: 15% above £5,000 secondary threshold
- Apprenticeship Levy: 0.5% on full pay (umbrella scenarios)
§ 03
Corporation Tax — unchanged from April 2023
- Small profits rate 19% on profits ≤ £50,000
- Main rate 25% on profits ≥ £250,000
- Marginal Relief between (effective ~26.5% on the marginal £)
§ 04
Dividend Tax — post April 2026 rise
- Allowance: £500 (uses band space but is tax-free)
- Basic rate: 10.75% (was 8.75% in 2025/26)
- Higher rate: 35.75% (was 33.75%)
- Additional rate: 39.35% (unchanged)
For specific HMRC source links, see our sources page. This is informational content, not regulated financial advice. For your own situation, consult a qualified accountant.