Salary Sacrifice Calculator (UK)

Salary sacrifice (also known as salary exchange) is a contractual arrangement in the UK where an employee agrees to give up a portion of their gross salary in exchange for a non-cash benefit of equivalent value provided by their employer. Because the sacrifice reduces the employee's gross salary, both the employee and the employer pay less National Insurance — and the employee also pays less income tax on the sacrificed amount. Pension contributions via salary sacrifice are the most common and tax-efficient application: contributions are classified as employer contributions, which means they do not attract employer NI (13.8%), employee NI (8%/2%), or income tax at the employee's marginal rate. For a 40% higher rate taxpayer contributing £10,000 to a pension via salary sacrifice, the total saving is £400 + £800 + £1,380 = £2,580 per year in combined income tax and NI, compared with contributing from net pay. Other common salary sacrifice benefits include: cycle-to-work scheme (up to £1,000 value tax and NI free), electric vehicle leasing (company car BIK tax is based on CO2 emissions — EVs have very low BIK rates, often making this more cost-effective than buying privately), childcare vouchers (legacy scheme, closed to new entrants since 2018), and ultra-low emission vehicles. Salary sacrifice reduces pensionable pay in some defined benefit schemes and may reduce mortgage affordability calculations, so these side effects should be considered. The arrangement must be set out in a contractual amendment and be a genuine, irrevocable reduction in gross salary.

Calkulon makes complex calculations simple — built for students and everyday problem-solvers.

1. 1The employee agrees in writing to reduce their gross salary by the sacrifice amount in exchange for a non-cash benefit (e.g., pension contribution, cycle to work, EV lease)
2. 2The reduced gross salary is then subject to income tax and National Insurance — both the employee and employer pay less NI as a result
3. 3The employer pays the benefit (e.g., pension contribution) directly — technically it is an employer contribution, not a personal contribution
4. 4The employee saves income tax at their marginal rate (20%, 40%, or 45%) on the sacrificed amount
5. 5The employee also saves employee NI at 8% (on salary up to £50,270) or 2% (above £50,270)
6. 6The employer saves 13.8% employer NI on the sacrificed amount — many employers pass some or all of this saving to the employee as an enhanced pension contribution
7. 7The net effect can be assessed by comparing take-home pay with and without salary sacrifice, considering also any changes to other income-related benefits

• !Forgetting to update the employment contract formally — a verbal agreement is not sufficient; salary sacrifice must be documented in writing
• !Not checking whether salary sacrifice reduces gross salary below the National Minimum Wage threshold
• !Assuming EV company cars via salary sacrifice are always cheaper than private purchase — the maths depends on the BIK rate, personal mileage, and any employment allowance
• !Overlooking the impact on mortgage affordability when planning large salary sacrifice amounts
• !Not asking the employer whether they share their NI saving as an extra pension contribution
• !Using salary sacrifice for benefits caught by OpRA rules without understanding that the tax saving may be limited