Salary Sacrifice Pension Calculator United Kingdom

Money put into a pension through salary sacrifice escapes both Income Tax and National Insurance. This calculator projects the pot you could build from a fixed monthly sacrifice, and shows what that contribution costs your take-home pay once those savings are counted.

How salary sacrifice works

You formally agree to reduce your contractual salary, and your employer pays the difference straight into your workplace pension. Because that part of your pay never reaches your bank account, it is never taxed: you avoid the Income Tax on it and the employee National Insurance charged on earnings. A contribution funded this way costs noticeably less than the same amount taken from net pay and topped up with basic rate relief.

With a personal pension paid from take-home pay, the provider claims basic rate tax for you, and higher rate taxpayers claim the rest through Self Assessment, but the National Insurance already deducted from your wages is never recovered. Salary sacrifice avoids that loss, which is why it is usually the better route where an employer offers it.

The real cost to your take-home pay

The key figure is the gap between what goes into the pension and what disappears from your payslip. The calculator works it out as the amount sacrificed multiplied by one minus your Income Tax rate minus your National Insurance rate.

A higher rate taxpayer sacrificing £300 a month saves 40% in tax and 2% in National Insurance, because earnings in the higher rate band are above the upper earnings limit, so take-home pay falls by about £174. A basic rate taxpayer sacrificing the same £300 saves 20% tax and 8% NI, so take-home pay falls by about £216. In both cases the full £300 goes into the pension.

How the pot is projected

The projection treats your monthly sacrifice as a regular contribution that compounds. Each month the balance earns a twelfth of your expected annual return, and the next contribution is added. Over 20 or 30 years the growth on early contributions can end up larger than the contributions themselves. The calculator uses the standard future value of a series formula, converting your annual return to a monthly rate and applying it to every month until you retire.

Returns are never guaranteed, so the figure is an illustration, not a promise. The pot you retire with depends on the returns you receive and the order they arrive in. Use the number as a planning guide and revisit it as your salary, contributions and outlook change.

A worked example

Suppose you sacrifice £300 a month for 20 years and assume a 5% annual return. You pay in £72,000 of contributions, and with monthly compounding the pot grows to about £123,310, so more than £51,000 of the final figure is investment growth. As a higher rate taxpayer, the £300 a month reduces your take-home pay by about £174, so you build that pot for a real outlay of a little under 60% of what goes in.

Assumptions and limitations

This is an estimate for planning, not personal advice. You choose the Income Tax and National Insurance rates, so pick the ones that match your earnings: 8% NI applies to earnings between the primary threshold and the upper earnings limit, and 2% above it. The projection assumes level contributions and a constant return every year, and growth is shown before inflation, so future amounts will buy less than the same sum today. It does not model the annual or tapered allowance, the effect of sacrifice on mortgage affordability or state benefits, employer National Insurance savings paid into your pension, or tax on the pension when you draw it. Check the current allowances and speak to a regulated adviser before committing to a large or long-term sacrifice.

About This Salary Sacrifice Pension Calculator

Use this salary sacrifice pension calculator to get an instant estimate based on the figures you enter. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.