UK Payroll • 2026-02-08 • By PayEase Team
How to Calculate PAYE Tax UK - Complete Guide 2026
A step-by-step 2026 guide to calculating PAYE tax in the UK, including tax codes, National Insurance rates, and worked examples.
What PAYE means for employers
PAYE, or Pay As You Earn, is the UK system employers use to deduct Income Tax and National Insurance from employee wages before payment. Every pay run must reflect the employee's tax code, pay frequency, and any relevant thresholds.
The goal is simple: deduct the correct amount in real time so employees do not face large underpayments later and employers stay aligned with reporting obligations.
Step 1: Confirm the employee's gross pay for the period
Start with gross pay for the chosen pay period. This includes regular salary or wages plus overtime, bonuses, commissions, and any taxable allowances. If an employee is paid monthly, use the monthly figure. If they are paid weekly, use the weekly figure.
Your tax calculation will only be accurate if gross pay is complete and correctly classified before deductions begin.
Step 2: Identify the correct tax code
The employee's tax code tells you how much income can be received before Income Tax applies and whether special circumstances exist. A common code like 1257L generally reflects the standard personal allowance, while other codes may indicate adjustments, emergency treatment, or multiple jobs.
If the wrong code is used, the PAYE result may still look plausible while remaining incorrect, so this step should never be skipped.
Step 3: Convert allowances and thresholds to the pay period
PAYE calculations work on pay-period values. If the employee is paid monthly, annual allowances and thresholds are divided into monthly equivalents. If paid weekly, use weekly equivalents. This ensures the calculation aligns with the actual payroll cycle.
For practical payroll work, software normally applies these fractions automatically, but it is still important to understand the logic when reviewing outputs.
Step 4: Calculate taxable pay and apply Income Tax bands
Subtract the applicable tax-free allowance for the period from gross taxable pay. The remainder is taxed across the employee's applicable Income Tax bands. The exact rate depends on the tax band and the jurisdictional rules being applied within the UK framework.
For example, if a monthly employee earns £4,000 gross and their period allowance is £1,047.50, the taxable amount is £2,952.50 before the PAYE band calculation is applied.
Step 5: Calculate National Insurance
National Insurance is separate from PAYE Income Tax. It uses its own thresholds and rates, and both employee and employer liabilities may apply. The employee contribution depends on earnings in the period and the NI category used.
In 2026, employers should verify current thresholds and category treatment before every new tax-year setup, because NI changes can have a direct impact on take-home pay and employer cost.
Worked example: monthly PAYE calculation
Assume a monthly employee earns £3,500 gross and uses tax code 1257L. First determine the monthly tax-free allowance. Then identify taxable pay, apply the PAYE rates to the taxable portion, and calculate National Insurance using the employee's category and monthly thresholds.
The final net pay is gross pay minus PAYE tax, employee National Insurance, pension deductions, and any other authorized deductions. The employer should also keep a separate record of employer NI for cost reporting.
Common PAYE mistakes to avoid
Most PAYE errors come from bad setup rather than bad math. Wrong tax codes, missed bonus pay, incorrect NI categories, and outdated thresholds are the biggest causes of rework.
A strong payroll process includes a review step that highlights unusual changes before the pay run is finalized.