2026/27 Pension Strategy

Pension Tax Relief Decoded: Net Pay, Relief at Source & Salary Sacrifice

Not all pension contributions are treated equally by HMRC. Our calculator models three distinct mechanisms — and the difference between them can cost (or save) you hundreds of pounds a year in National Insurance, Student Loan repayments and even the High Income Child Benefit Charge.

The Three Mechanisms at a Glance

For 2026/27, the way your employer processes pension contributions determines when tax relief is applied, who claims it, and whether you save National Insurance.

Feature	Salary Sacrifice	Net Pay	Relief at Source (RAS)
Deduction point	Before gross pay	Before tax (but after gross)	After tax (net pay)
Income Tax saved	Yes — reduces taxable gross	Yes — reduces taxable gross	Yes — 20% auto top-up
NI saved	Yes — lowers NI base	No	No
Student Loan saved	Yes — lowers SL base	No	No
HICBC / PA Taper	Reduced ANI	Reduced ANI	Reduced ANI
Higher-rate extra claim	Automatic	Automatic	Manual via Self Assessment
Common employers	Large private firms	NHS, Teachers, Police	Private pensions, Nest (some)

1. Salary Sacrifice

You agree to give up part of your gross salary in exchange for an employer pension contribution. Because the income never hits your payslip, it never gets taxed — and it never attracts National Insurance.

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How it affects your payslip

Most Tax Efficient

Your contractual gross drops by the sacrifice amount.
Income Tax is calculated on the lower gross.
NI is also calculated on the lower gross — saving 8% (or 2% above UEL) on the sacrificed amount.
Student Loan deductions are calculated on the lower gross.

💡 Why this matters for £100k+ earners

🎯Every £1 sacrificed reduces your Adjusted Net Income (ANI). If you are in the £100k–£125,140 Personal Allowance taper zone, sacrificing £1 saves you 60p–67.5p in tax plus 8p–2p in NI — an effective return of up to 69.5% in Scotland.

2. Net Pay Arrangement

The employer deducts your pension contribution directly from your gross pay before applying Income Tax. You automatically receive tax relief at your highest marginal rate — with no Self Assessment required.

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Public Sector Standard

NHS / Teachers / Police

Our calculator's presets reflect real public sector schemes:

NHS Band 5: 9.3% employee contribution (Net Pay)
Teacher M1: 7.4% employee contribution (Net Pay)
Police PC: 12.44% employee contribution (Net Pay)

The downside? Because the deduction happens after NI is calculated, you do not save National Insurance. Your NI base remains the full gross salary. However, you still benefit from reduced ANI for the Personal Allowance taper and HICBC.

3. Relief at Source (RAS)

Your pension contribution is taken from your net (after-tax) pay. The pension provider then claims 20% basic-rate tax relief directly from HMRC and adds it to your pot. If you are a higher-rate taxpayer, you must claim the additional 20% or 25% via Self Assessment.

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The 80/20 Split

Requires Action for Higher Earners

If you want £100 to go into your pension via RAS, you only pay £80 from your net salary. HMRC sends the remaining £20 to your provider. Our calculator models this precisely:

⚠️ Higher-Rate Trap with RAS

📝If you pay 40% or 45% tax, RAS only auto-delivers 20% relief. You must claim the remaining 20% (or 25% for Additional Rate) through your annual Self Assessment. Many higher earners unknowingly leave this money on the table.

One unique RAS feature: the basic rate band extension. HMRC treats the gross contribution as if it were taxed at 20%, effectively widening the amount you can earn before hitting the Higher Rate. Our calculator applies rasExtension = pensionEmployee to both England and Scotland band calculations.

Real-World Comparison: £40,000 Salary, 5% Pension

Here is how the same £2,000 annual pension contribution plays out under each method for a standard Category A employee in England.

Metric	Salary Sacrifice	Net Pay	Relief at Source
Taxable Gross	£38,000	£38,000	£40,000
Income Tax	£5,086	£5,086	£5,486*
NI (8% + 2%)	£2,714	£2,874	£2,874
Pension Cost to You	£2,000 (pre-tax)	£2,000 (pre-tax)	£1,600 (net)
Take-Home Pay	£28,200	£28,040	£28,040
NI Saved vs RAS	£160	£0	—

* RAS Income Tax is higher on payslip, but HMRC's £400 top-up means the net cost is identical to Net Pay for Basic Rate taxpayers. The £160 NI saving makes Salary Sacrifice the clear winner where available.

Interaction with HICBC & Student Loans

This is where pension mechanics become genuinely strategic — not just about retirement, but about immediate cash flow.

The High Income Child Benefit Charge (HICBC) begins when your Adjusted Net Income exceeds £60,000. It claws back 1% of Child Benefit for every £200 of income above £60,000, fully extinguishing it at £80,000.

Salary Sacrifice directly reduces ANI, potentially eliminating HICBC entirely.
Net Pay also reduces ANI, but without the NI saving.
RAS reduces ANI by the gross amount, even though you only funded 80% net.

Student Loans use a similar "gross minus sacrifice" base for Plan 1/2/4/5 calculations. A £5,000 sacrifice can save you £450 in Student Loan repayments (9%) on top of tax and NI savings.