Methodology, assumptions, and sources

Tax Calculator 365 provides illustrative estimates for UK employees paid via PAYE for the 2025/26 tax year. These results are not tax advice.

Scope

Income Tax: England/Wales/Northern Ireland (rUK) and Scotland bands.
Employee National Insurance: Class 1, category A (annualised).

Key assumptions

Annualised calculation (payroll period rounding may differ in real payslips).
Standard Personal Allowance rules (tapered above £100,000 where applicable).
No adjustments for non-standard tax codes, multiple employments, benefits in kind, or other payroll deductions.

Excluded (not currently modelled)

Student loans (Plan 1/2/4 and Postgraduate)
Dividends, savings interest, rental income, capital gains
Self-employment / Self Assessment
Employer National Insurance

Sources

Thresholds and rates should be reviewed against HMRC publications for the 2025/26 year. For transparency and ongoing maintenance, we recommend bookmarking the HMRC guidance pages for:

Income Tax rates and allowances (including Scottish rates)
National Insurance rates and thresholds

If you spot an issue, please contact us.