How to Calculate Your Salary Sacrifice Savings: Step-by-Step 2026/27

Step 1: Identify your marginal income tax rate

Your marginal income tax rate is the rate you pay on your highest-taxed income, specifically, on the pounds of salary you would be sacrificing. For 2026/27 (England, Wales, Northern Ireland): 20% basic rate applies to taxable income between £12,571 and £50,270. 40% higher rate applies to taxable income between £50,271 and £125,140. 45% additional rate applies above £125,140. For Scottish taxpayers the bands are different: 19% starter, 20% basic, 21% intermediate, 42% higher, 45% advanced, 48% top rate.

If your salary is comfortably within one band, your marginal rate is simply that band's rate. If your salary straddles a threshold (e.g. £51,000), the sacrifice may span two rates. In that case, calculate the saving in each band separately and add them together.

Step 2: Identify your marginal employee NI rate

Employee NI for 2026/27: 8% on earnings between £12,570 and £50,270 (the main rate). 2% on earnings above £50,270 (the upper rate). If your salary is between £12,570 and £50,270, all your sacrifice saves 8% NI. If your salary is above £50,270 and the sacrifice comes from that portion, it saves only 2% NI. If the sacrifice straddles the £50,270 threshold, split the calculation accordingly.

Step 3: Calculate the total saving

Add your marginal income tax rate and marginal NI rate together. This is your saving rate per pound sacrificed. Multiply by the sacrifice amount. Example: salary £38,000, annual sacrifice £2,400. Both rates: 20% income tax + 8% NI = 28%. Total saving: 28% × £2,400 = £672. Net cost of the £2,400 sacrifice: £2,400 − £672 = £1,728. Monthly impact: −£144 take-home to put £200 into pension.

Example 2: salary £52,000, annual sacrifice £3,000. The salary is £1,730 above the higher-rate threshold (£52,000 − £50,270). Assuming the sacrifice comes from the top of income: first £1,730 is at 40% + 2% = 42%; remaining £1,270 is at 20% + 8% = 28%. Saving: (£1,730 × 42%) + (£1,270 × 28%) = £726.60 + £355.60 = £1,082.20. Net cost: £3,000 − £1,082.20 = £1,917.80 per year (£159.82 per month).

Step 4: Add the employer NI saving (if passed on)

Employer NI is 15% on employee earnings above £5,000. If your employer passes any of this saving back to you as pension contributions, the pension receives more than the sacrifice amount. Employer NI on a £2,400 sacrifice: 15% × £2,400 = £360. At 100% passthrough: pension receives £2,760 at a take-home cost of £1,728. At 50% passthrough: pension receives £2,580 at a cost of £1,728. If no passthrough: pension receives £2,400 at a cost of £1,728. The calculation still shows an excellent return even without passthrough.

Step 5: Student loan adjustment (if applicable)

If you have a student loan, salary sacrifice also reduces your student loan repayments. For Plan 2 borrowers: repayment is 9% of income above £27,295. Each £1,000 sacrificed saves £90 in Plan 2 repayments (assuming income stays above the threshold). Add this to the income tax and NI saving for the full picture.

Example: salary £33,000, Plan 2 loan, £2,000 sacrifice. Income tax saving: £400. NI saving: £160. Student loan saving: 9% × £2,000 = £180. Total saving: £740. Net cost of £2,000 pension contribution: £1,260, an effective discount of 37%.

Using the calculator vs doing it manually

The manual calculation above gives accurate results for most people in a single tax and NI band. The calculator handles edge cases: salary straddling the higher-rate threshold, Scottish tax bands, personal allowance withdrawal above £100,000, student loan plans 1/2/4/5, and postgraduate loans. For an exact figure, particularly if your sacrifice is large relative to your salary, use the calculator rather than the approximate manual formula.

The pension salary sacrifice calculator on this site lets you enter salary, sacrifice amount, region, and student loan plan, and returns a complete breakdown of savings and net cost. It is particularly useful for modelling different sacrifice amounts to find the one that maximises pension input while keeping net pay above any critical floor (mortgage payments, spending commitments).