Every time a UK employee makes a pension contribution through salary sacrifice, their employer saves 13.8p in National Insurance for every pound redirected. On a £35,000 salary with a 5% employee pension contribution, that is an annual employer NI saving of £241.50 — generated entirely by the employee's decision to defer their own income into a pension. Most workers never see this money. It flows quietly into their employer's operating budget, unremarked and unchallenged.
This is not illegal. Employers are under no statutory obligation to pass their NI saving on to employees. But many do — when asked. And with the 2025/26 tax year closing on 5 April 2026, there are days remaining in which employees can negotiate this concession, adjust their salary sacrifice arrangements, and potentially add hundreds of pounds to their pension pot before the year resets.
What Salary Sacrifice Actually Is — and Why It Matters
Salary sacrifice is an arrangement in which an employee formally reduces their contractual salary in exchange for an employer-provided benefit — in this context, a pension contribution. The critical distinction from a standard employee pension contribution is that the money never reaches the employee as income. It is diverted before PAYE and National Insurance are calculated.
This creates a dual saving. The employee pays less Income Tax and less employee National Insurance on the sacrificed amount. For a basic-rate taxpayer, every £100 of pension contribution made through salary sacrifice costs approximately £68 in take-home pay, compared to £80 via a relief-at-source arrangement. The additional saving comes from the 12% employee NI that is also avoided.
The employer saving is separate and additional. When the employee's salary is reduced, the employer's National Insurance liability — charged at 13.8% on earnings above the secondary threshold — falls proportionally. This saving belongs to the employer. But it is derived from the employee's decision.
Modelling the Numbers on a £35,000 Salary
Consider an employee earning £35,000 per year who contributes 5% of salary (£1,750) to their pension through salary sacrifice.
Employee NI saving: 12% on £1,750 = £210 per year retained as additional net pay (compared to a non-sacrifice arrangement).
Employer NI saving: 13.8% on £1,750 = £241.50 per year saved by the employer on payroll costs.
If the employer passes their NI saving into the employee's pension as an enhanced contribution, the pension receives not £1,750 but £1,991.50 — an increase of 13.8% on the original contribution. Over a 30-year working life, with a conservative assumed annual growth rate of 5%, the compounded difference between these two scenarios is substantial.
| Scenario | Annual Pension Contribution | Projected Pot at 30 Years (5% pa) |
|---|---|---|
| Standard salary sacrifice, no NI pass-through | £1,750 | £116,400 |
| Salary sacrifice with full employer NI pass-through | £1,991.50 | £132,500 |
| Difference | £241.50 per year | +£16,100 |
For higher earners, the figures scale accordingly. On a £55,000 salary with a 5% contribution of £2,750, the employer NI saving rises to £379.50 per year. Over 30 years at 5%, the compounded difference exceeds £25,000.
These projections are illustrative and do not account for salary growth, changes in NI rates, or investment performance variability. But they demonstrate the material long-term impact of a negotiation that takes, in most cases, a single email to HR.
Why Most Workers Never Ask
The primary reason this saving goes unclaimed is simple: most employees do not know it exists. Salary sacrifice is presented to workers as a tax efficiency tool that benefits them — and it does — but the employer NI element is rarely disclosed in scheme documentation. Benefits guides, pension enrolment packs, and HR induction materials almost universally describe the employee's saving without mentioning the employer's.
A secondary barrier is the perception that pension negotiations are the exclusive preserve of senior executives. In practice, the employer NI pass-through is more commonly offered by smaller and mid-sized employers, where payroll decisions are made by individuals accessible to ordinary staff, than by large corporations with standardised benefits structures.
A third factor is timing. Salary sacrifice arrangements are typically reviewed annually, at the start of the new tax year. An employee who raises the question in June will often be told to wait until April. An employee who raises it in March — now — is asking at precisely the right moment.
The Exact Questions to Ask HR
The following questions are designed to be asked in writing — email or internal messaging — to create a documented record and to give the HR or payroll team time to consult finance before responding.
Question 1: "Does our company currently operate a salary sacrifice pension arrangement, and is it set up as a true contractual salary reduction?"
This establishes the baseline. Some employers describe contributions as salary sacrifice without implementing the formal contractual reduction required to generate the NI saving. If the arrangement is not genuinely structured as a salary reduction, neither party is saving NI, and the conversation ends here.
Question 2: "What is the company's policy on passing the employer National Insurance saving from salary sacrifice back to employees as additional pension contributions?"
This is the core question. Many HR teams will not have been asked this before. The response will fall into one of three categories: the company already passes the saving on (in which case, check your payslip confirms this); the company retains it but is open to discussion; or the company retains it as a matter of policy and is not willing to change.
Question 3: "If the company retains the employer NI saving, would it consider adding some or all of that saving to my pension pot as an enhanced employer contribution in the new tax year?"
This frames the request as a prospective change, reducing the sense of confrontation. It also anchors the conversation to the new tax year — a natural review point that gives the employer a logical mechanism for implementing the change.
Question 4: "Can you confirm in writing the total employer NI saving generated by my current salary sacrifice arrangement?"
This quantifies the sum at stake and signals that the employee understands the mechanics. It also creates a documented baseline for any future negotiation.
What Employers Are Legally Required to Do
To be clear: employers are not legally required to pass their NI saving on to employees. There is no statutory entitlement. However, HMRC guidance explicitly states that passing the employer NI saving to employees as pension contributions is a legitimate and tax-efficient use of the funds. There is no additional tax or NI consequence for the employer in doing so.
Employers who do pass the saving on typically do so in one of two ways: as a flat percentage added to the employer contribution rate, or as a direct match of the NI saving calculated on each individual's salary sacrifice amount. The latter is more equitable but more complex to administer.
The ISA and Pension Interaction
For workers approaching their annual pension allowance (currently £60,000 including all contributions, subject to the money purchase annual allowance where relevant), the additional NI saving may push total contributions towards the limit. In this scenario, any excess employer NI pass-through should ideally be redirected to an ISA — specifically a Stocks and Shares ISA — before the 5 April 2026 deadline, using the remaining £20,000 annual allowance.
This combination — maximised salary sacrifice pension contributions plus a fully funded ISA — represents the most tax-efficient structure available to UK employees and is the approach recommended by independent financial planners for workers in the £35,000–£80,000 income bracket.
What to Watch After 5 April 2026
The new tax year brings a reset of both ISA allowances and pension contribution windows. Employers who agree to implement an NI pass-through from April 2026 will typically need to update their payroll instructions before the first pay run of the new year. Employees should follow up in writing by mid-March to allow adequate processing time.
More broadly, the government's ongoing review of pension adequacy — expected to produce recommendations in the second half of 2026 — may include provisions that require greater transparency in salary sacrifice NI savings disclosure. Workers who act now, before any regulatory change, are best positioned to benefit from both the current rules and any future enhancements.
The bottom line: Your employer is almost certainly saving 13.8% of your pension contribution in National Insurance every month. A single, politely worded email to HR — sent before 5 April 2026 — is all it takes to begin the conversation that could add over £16,000 to your retirement pot.
This article is for informational purposes only and does not constitute financial advice. Pension and tax rules depend on individual circumstances and may change. For personalised guidance, consult a regulated financial adviser or visit moneyhelper.org.uk.