National Insurance: Employer and Employee Guidance

National Insurance is one of those unavoidable facts of business life in the UK. Whether you’re employing your first member of staff or scaling a team, NI affects what you pay, what your employees take home, and how you stay compliant. But it’s more complex than just pressing a button on your payroll software. This guide strips away the jargon and gives you the practical, detailed answers you need: how National Insurance works, what both employers and employees must do, the latest rates and rules, and exactly how to get it right—first time, every time.

National Insurance (NI) is a system of contributions paid by workers and employers in the UK, funding key state benefits including the State Pension, statutory sick pay, maternity allowance, and certain unemployment benefits. For businesses, NI is not optional: it's a legal requirement, and failing to understand or meet your obligations can result in fines, penalties, and even criminal prosecution. For employees, NI determines entitlement to contributory benefits and directly affects take-home pay.

Unlike Income Tax, which funds general government spending, National Insurance is ring-fenced for social security purposes. Most people pay NI through PAYE (Pay As You Earn), but there are special rules for the self-employed and company directors. As an employer, you must calculate, deduct, and pay both your own employer contributions and your employees’ deductions to HMRC, usually every month.

NI is not just a payroll deduction—it impacts your overall employment costs, can influence hiring decisions, and determines eligibility for certain government incentives. Understanding exactly how NI works is crucial for business planning and compliance.

National Insurance is not a one-size-fits-all tax. The amount and type you pay depends on your employment status, age, and earnings. Both employers and employees must understand the different NI 'classes', as each has its own rates, thresholds, and rules. For most businesses, the focus is on Class 1 contributions (for employees), but self-employed people, company directors, and others fall under different classes.

Class 1 National Insurance contributions are deducted from employees’ pay and paid by employers for most staff aged 16 to State Pension age who earn above the 'Lower Earnings Limit' (LEL). The government sets these thresholds and rates each tax year, and they can change annually. There are also special rules for apprentices, under-21s, and employees over State Pension age.

Other classes include Class 2 and Class 4 (for the self-employed) and Class 3 (voluntary contributions, usually to fill gaps for pension entitlement). As an employer, you’re mainly responsible for Class 1, but understanding the broader context helps you answer employee questions and avoid confusion.

National Insurance rates and thresholds change regularly, so you need to check each tax year’s figures. As of April 2026, the main rates for Class 1 (employee and employer) NI are as follows. These figures are critical for payroll calculations and compliance.

For employees, NI is only paid on earnings above the Primary Threshold (PT), and the rate is lower for higher earners above the Upper Earnings Limit (UEL). For employers, NI is paid on earnings above the Secondary Threshold (ST). Special rules apply for apprentices under 25, employees under 21, and certain veterans.

Failing to use the correct thresholds can result in under- or overpayment, so always check the latest HMRC guidance or payroll software updates.

• Check the HMRC website for annual updates to NI rates and thresholds.
• Payroll software should update automatically, but always confirm after April.
• Special reliefs (e.g., Employment Allowance, apprentice exemptions) can lower your bill.
• Directors have annual rather than weekly/monthly thresholds – handled differently in payroll.
• Class 1A/1B NI must be reported and paid separately (e.g. on company cars, medical insurance).

Employers must register with HMRC before taking on staff, operate PAYE correctly, calculate and deduct NI every pay period, and pay both employer and employee contributions to HMRC. This is not just admin—it’s a legal requirement, and mistakes can be costly.

Every time you pay an employee above the Lower Earnings Limit (£6,396 for 2026/27), you must operate PAYE, deduct NI, and issue a payslip showing the deductions. You must also report pay and deductions to HMRC on or before each payday using Real Time Information (RTI). This applies even to directors and family members if they’re on the payroll.

Employers pay NI to HMRC monthly (or quarterly if your average PAYE bill is less than £1,500 per month). Payment deadlines are strict: usually the 22nd of the month if paying electronically, or the 19th if paying by post. Late payments can trigger interest and penalties.

• Register as an employer with HMRC as soon as you hire your first employee.
• Set up and use payroll software that handles PAYE, NI, and RTI submissions.
• Keep accurate records of employees’ pay, NI numbers, and deductions for at least 3 years.
• Pay Class 1A NI (on benefits) annually by 22 July following the tax year.
• Provide employees with a P60 at the end of each tax year, showing their NI contributions.

Company directors are treated differently for NI purposes. Rather than weekly or monthly thresholds, directors are assessed on an annual earnings basis. This often leads to higher deductions later in the year if you pay directors with irregular salaries or bonuses, so planning is key.

Apprentices under 25 and employees under 21 benefit from reduced employer NI. For these groups, employers pay 0% Class 1 NI on their earnings up to the Upper Secondary Threshold (£50,270 for 2026/27), though employee deductions still apply. This is designed to encourage youth employment and apprenticeships, but you must report the apprentice status correctly in your payroll software and keep evidence (such as apprenticeship agreements) in case of HMRC inspection.

Other edge cases include employees with more than one job, workers on zero-hours contracts, and those with multiple sources of NI (such as being both employed and self-employed). Each situation can affect how NI is calculated and reported. Always check HMRC guidance or seek professional advice for anything unusual.

• Directors’ NI can be calculated using the annual method (recommended) or alternative method (pro-rata, then annual adjustment).
• For apprentices, keep written evidence of apprenticeship status and training provider.
• Employees over State Pension age pay no employee NI, but you still pay employer NI.
• Employees with multiple jobs may hold a CA2700 certificate to avoid overpaying NI.
• If an employee earns less than the LEL, they may not build up NI credits for State Pension.

National Insurance isn’t just about cash wages. If you provide taxable benefits in kind—such as company cars, health insurance, or staff entertainment—you may have to pay Class 1A or 1B employer NI. This is separate from the main NI and must be reported and paid annually, usually via the P11D and P11D(b) forms.

Class 1A NI is paid on most taxable benefits (e.g. company cars, private medical insurance) and is due at a flat rate (currently 13.8%) with payment due by 22 July following the end of the tax year. Class 1B NI applies if you’ve agreed a PAYE Settlement Agreement (PSA) with HMRC to cover certain minor or irregular expenses. These are both employer-only charges—employees do not pay them.

Failing to correctly report and pay Class 1A/1B NI is a common compliance failure. Make sure you understand which benefits attract NI, keep detailed records, and file all relevant forms by the deadlines. Errors or omissions can trigger HMRC enquiries and penalties.

• File P11D forms for each employee receiving taxable benefits by 6 July after the tax year.
• Submit the P11D(b) form, which declares the total Class 1A NI due, by the same deadline.
• Pay Class 1A NI by 22 July (electronic payment) or 19 July (cheque).
• If using a PSA, ensure you include all relevant expenses and pay Class 1B NI as agreed.
• Not all staff benefits are taxable—some, like workplace pension contributions, are exempt.

Many small businesses run into trouble with National Insurance simply because they misunderstand the rules, fail to keep up with rate changes, or don’t set up payroll correctly. The most common errors include missing payment deadlines, using out-of-date rates, wrongly classifying staff, or failing to report benefits in kind.

Another frequent issue is not updating employee details—such as NI numbers, addresses, or employment status—which can lead to mismatches with HMRC records and delays in processing. Using manual calculations or outdated spreadsheets also increases the risk of error. Most reputable payroll software is updated automatically each April, but it’s still your responsibility to check and understand the numbers.

HMRC can impose penalties for late or incorrect payments, failure to operate PAYE, or under-reporting benefits. In serious cases, directors can be held personally liable. It’s worth investing a bit more time—or professional support—to get NI right from the start.

The government offers several NI reliefs to help small businesses manage employment costs. The most valuable is the Employment Allowance: from April 2026, you can claim up to £5,000 per year off your employer NI bill if your total Class 1 NI liability was less than £100,000 in the previous tax year. This is claimed via your payroll software and reduces your monthly NI payments until the allowance is used up.

There are also exemptions for employing apprentices under 25, employees under 21, and eligible armed forces veterans (for their first 12 months in civilian employment). These reliefs are designed to stimulate employment and reduce costs for growing businesses, but you must claim them correctly and keep records of eligibility.

Be aware: not all businesses can claim every relief. For example, if you’re a director-only company with no other employees, you can’t claim Employment Allowance. HMRC provides detailed eligibility checkers and guidance on GOV.UK.

NI interacts with workplace pensions in several subtle but important ways. Statutory pension contributions are not subject to NI, but salary sacrifice pension schemes can reduce both employer and employee NI bills. This is because NI is calculated on post-sacrifice salary, not gross pay.

Many small businesses use salary sacrifice to help employees boost their pension savings and reduce overall NI costs. However, you must set up the arrangement correctly and communicate the implications to staff. Employees benefit from higher pension contributions and lower NI, but it can affect statutory entitlements (like maternity pay or redundancy) which are calculated on post-sacrifice pay.

Always check the latest guidance from The Pensions Regulator and HMRC before implementing salary sacrifice schemes. Incorrectly run schemes can result in backdated NI liabilities and penalties.

• Pension contributions under automatic enrolment are NI-free for both employer and employee.
• Salary sacrifice schemes must be documented and communicated to all staff.
• Reducing gross salary via salary sacrifice lowers both employer and employee NI.
• Statutory payments (e.g., SMP, SSP) may be affected by reduced reference pay.
• HMRC can challenge arrangements that are primarily tax-motivated—ensure you follow the rules.

Keeping accurate records is not just good practice—it’s a legal requirement. Employers must keep detailed payroll and NI records for at least three years after the end of the relevant tax year. This includes payslips, RTI submissions, P11D forms, apprenticeship agreements, and evidence of any NI reliefs claimed.

HMRC can ask to inspect your records at any time, and you must be able to provide evidence of how NI was calculated, why reliefs were claimed, and how benefits in kind were reported. Poor record-keeping is one of the most common reasons for compliance failures and penalties.

If HMRC finds errors, you may have to repay underpaid NI plus interest and penalties. In serious cases, directors can be made personally liable. If you discover a mistake, notify HMRC promptly—voluntary disclosure can reduce penalties.

• Keep digital and/or paper copies of all payroll records for at least three years.
• Store evidence of NI numbers, dates of birth, employment contracts, and relief eligibility.
• Check all RTI submissions for accuracy before sending.
• If you use a payroll bureau or accountant, confirm they’re submitting and paying on time.
• Respond promptly to any HMRC queries or compliance checks.