Methodology

AfterTaxSalary uses deterministic formulas based on published HMRC rates for 2025/26. It estimates PAYE income tax, employee National Insurance, student loan repayments and pension deductions for planning and salary comparison. It is not payroll software and it is not financial advice. This page documents every assumption the calculator makes so you can understand and correct for your own situation.

Last reviewed: 20 March 2026 · Maintained by James Whitfield

rUK income tax bands (2025/26)

Applies to England, Wales and Northern Ireland. Scotland uses different bands — see below.

Band	Taxable income	Rate
Personal allowance	Up to £12,570	0%
Basic rate	£12,571 – £50,270	20%
Higher rate	£50,271 – £125,140	40%
Additional rate	Over £125,140	45%

Personal allowance tapers at a rate of £1 for every £2 earned above £100,000, reaching £0 at £125,140.

Scottish income tax bands (2025/26)

Scotland uses five bands set by the Scottish Parliament. National Insurance uses UK-wide rates regardless of region.

Band	Taxable income	Rate
Personal allowance	Up to £12,570	0%
Starter rate	£12,571 – £15,397	19%
Basic rate	£15,397 – £27,491	20%
Intermediate rate	£27,491 – £43,662	21%
Higher rate	£43,662 – £75,000	42%
Advanced rate	£75,000 – £125,140	45%
Top rate	Over £125,140	48%

Scottish personal allowance taper mirrors rUK: £1 withdrawn per £2 above £100,000.

National Insurance (employee, 2025/26)

The calculator assumes NI Category A (employed, not contracted out). NI is calculated on an annual equivalent basis for static salary pages; the full calculator uses monthly equivalent logic.

Band	Annual earnings	Rate
Below primary threshold	Up to £12,570	0%
Main rate	£12,571 – £50,270	8%
Above upper earnings limit	Over £50,270	2%

Source: HMRC National Insurance rates and categories. NI rates are UK-wide — they do not vary by region.

Student loan repayment thresholds (2025/26)

Repayments are calculated at the applicable rate on income above the threshold. All rates apply to Plan or Postgraduate Loan separately; if you hold both, repayments are calculated independently and sum together.

Plan	Who it applies to	Threshold	Rate
Plan 1	Pre-2012 England/Wales; NI; some Scottish	£24,990	9%
Plan 2	Post-2012 England/Wales (up to 2022 entry)	£27,295	9%
Plan 4	Scottish post-2012 graduates	£31,395	9%
Plan 5	England entry from Sept 2023 onwards	£25,000	9%
Postgraduate Loan	Masters/PhD loans	£21,000	6%

Source: HMRC student loan repayment thresholds.

Pension contribution logic

The calculator supports two pension contribution types:

Salary sacrifice — contribution is deducted from gross pay before income tax and NI are calculated. Reduces both tax and NI. The calculator models this by subtracting the sacrifice amount from gross before applying any other calculation.
Standard (net pay or relief at source) — contribution is taken from pay after PAYE deduction. Income tax relief is applied (treated as reducing taxable income by the contribution amount), but NI is not saved. The calculator models this by applying income tax relief but leaving NI calculated on the pre-contribution gross.

The calculator does not model employer contributions or the annual allowance limit (£60,000 for 2025/26). It is a planning estimate only.

Calculation sequence

Start with gross annual salary.
If salary sacrifice pension is selected, subtract pension contribution from gross to get adjusted gross for tax purposes.
Apply the selected region's income tax bands to adjusted gross, using the personal allowance derived from the tax code (default: £12,570 / code 1257L). Apply taper if adjusted gross exceeds £100,000.
Calculate employee NI on the original gross pay (before salary sacrifice) using the Category A schedule. NI is not affected by salary sacrifice in the calculator's model.
Apply student loan repayment on gross pay (before sacrifice) above the plan threshold at the plan's rate.
If standard pension (not sacrifice) is selected, subtract contribution from take-home after tax and NI.
Derive annual, monthly, weekly (÷52) and daily (÷260 working days) take-home outputs.

Note: employer payroll systems calculate NI monthly. For steady salaries the annual and monthly-equivalent approaches produce identical results. Bonuses and irregular pay periods are not modelled.

Default assumptions on salary pages

Static salary pages (e.g. /take-home-pay/35000) use the following defaults to produce server-rendered comparable figures:

Tax region: England/Wales/Northern Ireland (rUK bands)
Tax code: 1257L (standard personal allowance)
Student loan: none
Pension: none
NI category: Category A (standard employed)

To model your actual situation, use the full calculator which accepts all these inputs.

Known limitations

Does not model benefits-in-kind (company car, private medical) which alter the effective personal allowance via K codes.
Does not model multiple employment or cumulative NI across multiple jobs.
Bonus payments are not modelled — one-off payments are taxed differently in real payroll (annualised in the month paid).
Self-employed income, dividend income and rental income are outside scope.
Does not model Class 1A or employer NI contributions.
Marriage Allowance and Blind Person's Allowance are not modelled.