Gross pay vs net pay
In brief: Your gross salary is what your employer agrees to pay you. Your net take-home is what you actually receive after income tax, National Insurance, and any other deductions. Understanding the gap between gross and net is fundamental to understanding what you actually have available to save, invest, or spend.
Your payslip shows the journey from gross to net. The main statutory deductions are:
- Income tax — collected by your employer via the PAYE (Pay As You Earn) system
- National Insurance (Employee Class 1) — a separate deduction for social insurance
Other deductions may include pension contributions, student loan repayments, childcare vouchers, and any voluntary deductions (share schemes, cycle to work, etc.).
Gross salary is the starting point for income tax and NI calculations, and also the figure used for many other purposes: mortgage affordability assessments, life insurance multiples, and some state benefit calculations.
Income tax on employment (PAYE)
Employment income is subject to income tax, collected via the PAYE (Pay As You Earn) system. Your employer deducts tax from each pay packet based on the tax code HMRC issues for you, and pays it directly to HMRC on your behalf.
How your tax code works
Your tax code tells your employer how much tax-free income to allow before deducting tax. The most common code is 1257L (2024/25 and 2025/26), which corresponds to the standard Personal Allowance of £12,570. The letter indicates how the allowance is applied (L = standard allowance, subject to normal rules).
Adjustments to your tax code can reflect:
- Untaxed income (rental income, freelance work) — reduces the code
- Benefits in kind (company car, private medical insurance) — reduces the code
- Underpaid tax from previous years — reduces the code
- Additional allowances (blind person's allowance) — increases the code
If HMRC issues the wrong code, you may pay too much or too little tax during the year. Overpayments are refunded; underpayments are usually collected via the following year's code or through Self Assessment.
Emergency tax codes
If you start a new job without providing a P45, your employer may operate an emergency tax code (suffix W1 or M1, meaning "week 1 / month 1"). Emergency codes treat each pay period in isolation — they do not account for personal allowance used earlier in the year — which can result in too much tax being deducted. This is corrected when HMRC issues the correct code.
Employment income in the context of retirement
Understanding how employment income stacks with other income sources is important for retirement planning. In the years leading up to retirement, a part-time salary, consultancy income, or freelance work will be added to pension drawdown and other income to determine the total tax position. The combined income level determines which tax bands apply.
National Insurance
National Insurance (NI) is a separate system of contributions that funds the State Pension and certain contributory benefits. It is not income tax, but it functions like a payroll deduction and is collected via PAYE.
Employee Class 1 contributions (2025/26)
| Earnings band | Employee NI rate |
|---|---|
| Below £12,570 (Lower Earnings Limit equivalent) | 0% |
| £12,570 to £50,270 | 12% |
| Above £50,270 | 2% |
Employee NI applies to earnings in each pay period. Unlike income tax, NI does not consider annual income — it is assessed week by week or month by month.
Employer Class 1 contributions
Your employer also pays NI on your earnings, but this does not appear on your payslip — it is a cost to the employer above and beyond your gross salary. The employer rate is 13.8% on earnings above the Secondary Threshold (£9,100 per year, rising from April 2025).
This employer NI cost makes salary sacrifice (described below) attractive to employers as well as employees.
What NI pays for
NI contributions are the mechanism by which you build entitlement to the State Pension and certain contributory benefits (Jobseeker's Allowance, Employment and Support Allowance, Maternity/Paternity Pay). You need 35 qualifying years for the full new State Pension. A year is qualifying if your earnings are above the Lower Earnings Limit (£6,396 in 2024/25).
You stop paying employee NI when you reach State Pension age, even if you continue working.
Brief historical note: contracting out
Before April 2016, some employees were "contracted out" of the additional State Pension in exchange for reduced NI contributions (and lower State Pension entitlement). This system is now closed, but anyone with a contracted-out history will have a lower State Pension entitlement, which will be reflected in their State Pension forecast.
Salary sacrifice
Salary sacrifice (also called salary exchange) is an arrangement where you agree to give up a portion of your gross salary in exchange for a non-cash benefit — most commonly employer pension contributions.
How it works
Instead of receiving £50,000 in salary, you agree with your employer to sacrifice £5,000. Your contractual gross salary becomes £45,000. Your employer contributes the £5,000 directly into your pension.
Tax and NI savings
Because your gross salary has reduced, you pay less income tax and less National Insurance on the sacrificed amount. Your employer also pays less employer NI.
For a basic rate taxpayer sacrificing £5,000:
- Income tax saving: £5,000 × 20% = £1,000
- Employee NI saving: £5,000 × 12% = £600
- Total employee saving: £1,600
- Employer NI saving: £5,000 × 13.8% = £690 (employer benefit, sometimes passed on to employee as additional pension contribution)
The total saving of £1,600 means a £5,000 pension contribution has an effective net cost of £3,400 — compared to contributing £4,000 from net pay and claiming basic rate relief (which only returns the tax, not the NI).
Worked example
| Without sacrifice | With sacrifice | |
|---|---|---|
| Gross salary | £50,000 | £45,000 |
| Employee pension contribution | £5,000 (net) | £0 |
| Gross salary after pension | £50,000 | £45,000 |
| Income tax (approx.) | £7,486 | £6,486 |
| Employee NI (approx.) | £4,284 | £3,684 |
| Net take-home | ~£38,230 | ~£34,830 |
| Pension funded | £4,000 (after relief) | £5,000 (employer contribution) |
The salary sacrifice route puts more into the pension for the same net cost.
Important side effects of salary sacrifice
Salary sacrifice reduces your contractual gross salary, which can affect:
- Mortgage affordability — lenders assess affordability based on actual contractual salary. A reduced gross salary may lower the maximum mortgage available.
- Statutory Maternity/Paternity Pay — statutory payments are based on average weekly earnings, which are derived from actual salary. Reduced salary means lower statutory pay.
- Life cover / death in service — if your employer provides life cover as a multiple of salary (e.g., 4× salary), salary sacrifice reduces the insured amount.
- State Pension — your NI record is still credited based on the full original salary, provided your post-sacrifice salary remains above the Lower Earnings Limit. This is because pension contributions made via salary sacrifice are treated as employer contributions, and HMRC has confirmed the NI record is protected.
Pension auto-enrolment
All employers must automatically enrol eligible workers into a qualifying workplace pension. The minimum contribution under auto-enrolment is:
- 5% employee contribution (including 1% tax relief from the government)
- 3% employer contribution
- Total: 8% of qualifying earnings
Qualifying earnings for auto-enrolment are earnings between £6,240 and £50,270 per year (2025/26). Contributions are calculated on this band, not total earnings. Some employers use a different definition of pensionable pay, which can result in higher effective contributions.
You have the right to opt out of auto-enrolment, but your employer must re-enrol you every 3 years. Opting out permanently requires active action every 3 years. If you opt out, you lose the employer contribution — effectively declining a portion of your total remuneration.
Employment income in retirement
Many people continue to work in some capacity in early retirement — part-time employment, consultancy, or freelance work. This "phased retirement" income is treated identically to employment income for tax purposes: it is added to pension drawdown, annuity income, State Pension, and other sources to determine the overall income tax position.
Working in retirement while taking pension drawdown can create a tax complication if total income pushes into a higher tax band. It can also trigger the Money Purchase Annual Allowance (MPAA): once you start flexibly accessing a defined contribution pension, the annual allowance for future money purchase pension contributions drops to £10,000 (from £60,000). Salary sacrifice pension contributions are money purchase contributions — so employment in retirement alongside pension drawdown requires careful tracking.
These projections are for modelling purposes only. They do not constitute financial advice. Tax rules are subject to change. Please consult a qualified financial adviser before making financial decisions.