Methodology and data sources.

Every calculation on Pension Bible can be reproduced from public sources. This page explains where the numbers come from, the assumptions we make, and how often we update them.

Tax year

All calculators use the 2025/26 UK tax bands unless otherwise stated. Tax bands are reviewed in April when a new tax year begins.

Sources

• Income tax bands and rates: gov.uk/income-tax-rates
• National Insurance rates: gov.uk/national-insurance-rates-letters
• Student loan thresholds: gov.uk/repaying-your-student-loan
• Pension provider fees: each provider's published fee schedule, cited and dated on the provider's page.

Assumptions

• Salary calculators assume your salary is your only source of UK taxable income, and do not account for benefits in kind or dividends.
• Personal allowance is tapered above £100,000 (£1 of allowance lost per £2 of income above £100k), as per HMRC rules.
• Compound projections use a flat nominal growth rate (typically 5%) unless otherwise stated. This is illustrative — real returns will vary, and inflation will erode purchasing power.
• Scottish income tax bands differ from rUK. Calculators that quote tax flag this in their caveats.

Updates

Tax bands are reviewed every April. Provider fee data is re-verified quarterly. If you spot an error, email us at hello@pensionbible.co.uk and we'll fix it.