NEST RAS on Payslip: Meaning, Calculation & How to Switch

Why NEST defaults to Relief at Source

If your workplace uses the National Employment Savings Trust (NEST) for statutory auto-enrolment, your contributions default to a framework HMRC calls Relief at Source (RAS). NEST chose RAS as its default because it works for every employee on the books — including those earning below the personal allowance, who would otherwise lose access to tax relief under a net-pay scheme.

The trade-off is structural: Relief at Source captures the standard 20% basic-rate tax relief on your contribution, but it leaves two material savings on the table — Class 1 employee NI on the sacrificed slice, and the automatic higher-rate top-up for anyone whose income crosses the higher-rate threshold.

The default auto-enrolment math (2026/27)

Statutory minimum contributions sit at 8% of qualifying earnings — the gross band between the £6,240 lower earnings level and the £50,270 upper earnings limit. Your employer covers 3%; you cover the remaining 5%.

Under Relief at Source, the 5% employee slice is processed in three steps:

1. 4% leaves your net pay — after PAYE income tax and Class 1 NI have already been deducted from the gross.
2. NEST sweeps that cash across to your personal pension pot.
3. HMRC tops it up by 1% — the 20% basic-rate relief on the gross-equivalent contribution — landing in the pot a few weeks later.

For a basic-rate earner the maths nets out correctly. For a higher-rate earner it does not: NEST only ever reclaims the basic 20%, so the additional 20% relief due on the contribution has to be claimed manually through Self Assessment. Many higher-rate earners never make that claim and silently lose the relief.

How NEST Salary Exchange changes the pipeline

When your employer migrates the scheme onto a NEST Salary Exchange footing, your 5% employee contribution disappears from the employee section of the payslip. In return, you contractually reduce your gross salary by an equivalent 5%, and the employer routes the full 8% into NEST as a single consolidated employer contribution.

Because your contractual gross is lower before payroll runs, the sacrificed slice never enters the tax or NI calculation window:

Standard Pay: Gross → PAYE + 8% employee NIC → pension deducted from net.
Salary Exchange: Gross − 5% pension → PAYE + NIC applied to the remainder.

NEST stops claiming the 1% tax-relief wrapper because the relief has already been captured at source — by preventing HMRC from taxing that slice of income in the first place. Higher-rate earners get their full 40% relief automatically, with no Self Assessment claim required.

The dual NI windfall

Salary sacrifice unlocks two separate NI savings on the same pound, benchmarked against the 2026/27 rates:

• Employee NI saving. You avoid the 8% Class 1 employee NI on the sacrificed slice if your income sits inside the main band, or 2% on any slice above the Upper Earnings Limit. The saving is automatic — it appears as a higher take-home figure on the next payslip.
• Employer NI saving. The employer avoids the 15% Secondary Class 1 NI on the same slice. Progressive employers operate a reinvestment pass-back, returning some or all of that saving into the pension as an additional employer contribution — a free uplift on top of the existing 8%.

Worked example — a £42,000 basic-rate earner

Take an employee on £42,000 gross, contributing the default 5% (£1,789) against qualifying earnings of £35,790. Switching from Relief at Source to NEST Salary Exchange does three things at once:

• Take-home rises by roughly £143 a year — the 8% employee NI saving on the £1,789 sacrificed slice.
• The pension pot is unchanged in headline cash terms — the same total 8% lands inside NEST every month.
• If the employer passes back its 15% saving, an additional £268 a year drops into the pot at no cost to the employee.

For a higher-rate earner sacrificing into the 40% band, the take-home delta runs materially larger because the 40% income-tax relief is captured automatically — no Self Assessment reconciliation needed.

Caveats worth knowing

Salary sacrifice lowers your headline contractual gross, and that downstream figure is the one some other systems read. Three to check before signing the variation letter:

• Mortgage affordability. Lenders typically gross your sacrifice back up when assessing affordability, but a handful still read the post-sacrifice figure on the payslip. Confirm with the lender before you commit, particularly on a fixed-rate remortgage window.
• Statutory pay floors. Statutory Maternity Pay, Statutory Sick Pay and the National Minimum Wage are calculated on the post-sacrifice gross. If sacrifice drops your hourly rate below NMW, the variation is invalid — your employer's payroll software should refuse it.
• Salary-linked benefits. Life cover, income protection and bonus percentages are sometimes pegged to contractual gross. Check the benefits schedule — many employers explicitly uplift these to the pre-sacrifice figure, but the language varies.

How to actually trigger the switch

NEST Salary Exchange is an employer-level toggle. Individual employees cannot opt in unilaterally — the company has to enable the framework, issue a contract variation letter, and run a one-off payroll reconfiguration. Most HR or finance teams will have already evaluated it; the employer NI saving usually pays for the implementation cost inside the first year.

If your scheme is still on Relief at Source, raise it with your HR business partner. The conversation is typically short: the employer captures a permanent 15% NI saving on every qualifying contribution, and you capture the employee NI plus automatic higher-rate relief. The underlying pension pot is unchanged.