How is pro-rata salary calculated?

Pro-rata salary is your full-time equivalent salary multiplied by the fraction of hours or days you work. For example, if the full-time salary is £30,000 and you work 3 days out of 5, your pro-rata salary is £18,000.

Does pro-rata affect my tax code?

Working fewer hours does not itself determine your tax code. HMRC may change the code if your expected annual income, allowances or other circumstances change.

Do I pay less National Insurance on a pro-rata salary?

Employee NI is usually assessed separately for each pay period. For standard employees in 2026/27, the primary threshold is £242 a week or £1,048 a month. A short period does not receive the full £12,570 annual threshold.

Calculator

Pro-Rata Salary Calculator

Estimate annual part-time take-home pay from your full-time salary and working pattern. Date ranges show gross pay only; period deductions depend on your payroll history.

Frequently Asked Questions

How is pro-rata salary calculated?: Pro-rata salary is your full-time equivalent salary multiplied by the fraction of hours or days you work. For example, if the full-time salary is £30,000 and you work 3 days out of 5, your pro-rata salary is £18,000.
Does pro-rata affect my tax code?: Working fewer hours does not itself determine your tax code. HMRC may change the code if your expected annual income, allowances or other circumstances change.
Do I pay less National Insurance on a pro-rata salary?: Employee NI is usually assessed separately for each pay period. For standard employees in 2026/27, the primary threshold is £242 a week or £1,048 a month. A short period does not receive the full £12,570 annual threshold.

How to use this estimate properly

This tool is strongest when you need a quick UK PAYE estimate for changed hours, reduced days, or a partial-year salary rather than a contractual HR calculation.

Helps translate part-time or partial-year gross pay into likely net pay
Keeps the same tax and NI treatment as the main salary engine
Useful when comparing a full-time role with a reduced-hours or mid-year scenario

Read the modelling assumptions →Open the full salary calculator →

Useful background guides

These pages help if the pro-rata result raises questions about tax code treatment, deductions, or how the lower pay may appear on a payslip.