Employment Tax, IR35 and Benefits in Kind in Practice

Employment taxes touch every business that engages people, and they are among the most error-prone obligations a finance function carries. The business deducts and pays over income tax and National Insurance for its employees, pays its own employer’s National Insurance, values and reports benefits, handles expenses, decides how contractors are treated, and reports share awards. The rules change most years, HMRC enforces them actively, and mistakes tend to repeat every pay period until someone spots them, so a small error can become a large liability.

This guide is written for in-house tax professionals, Financial Controllers and payroll leads who need a working understanding of the area. It covers the scope of employment taxes, benefits in kind and the move to payrolling, off-payroll working and IR35, the umbrella company rules that took effect in April 2026, employment-related securities, PAYE Settlement Agreements, and the practical controls that keep the business compliant. It is an orientation rather than a technical manual: thresholds and rates change, and HMRC’s current guidance is the reference for the detail. If you are deciding who should own this work, our guide on when to bring employment tax in-house covers the hiring decision.

The Scope of Employment Taxes

At the core sits PAYE. The employer deducts income tax and employee Class 1 National Insurance from pay, adds its own employer’s Class 1 National Insurance, and reports each payment to HMRC in real time through a Full Payment Submission on or before payday. Employer’s National Insurance rose to 15% in April 2025, which has made the cost of getting the payroll base wrong more expensive. Student loan deductions, statutory payments, pension auto-enrolment and correct tax codes all run through the same machinery; our guide to decoding HMRC tax codes explains how coding notices feed the payroll.

The scope goes well beyond salary. It includes benefits in kind, which are generally taxable and must be valued and reported; expenses, where the rules decide which reimbursements are tax-free; the off-payroll working rules for contractors who work through their own companies; the umbrella company rules for temporary labour; shares and options awarded to employees; and settlement arrangements for minor or irregular benefits. Most errors arise here rather than in the PAYE on salary, because these areas are less routine and often sit outside payroll.

Day-to-day processing usually sits with payroll. The Payroll Clerk runs the pay cycle and supports year-end reporting, while the Payroll Manager owns RTI compliance, the payroll calendar and the interface with IR35 and umbrella arrangements. The technical judgements — status decisions, benefit valuations, share scheme reporting, HMRC enquiries — normally sit with an in-house tax professional or the Financial Controller, supported by external advisers.

Benefits in Kind

Benefits in kind are the non-cash benefits a business gives its employees: company cars and fuel, vans, private medical insurance, beneficial loans, living accommodation and a long list of smaller perks. The general principle is that they are taxable. The employee pays income tax on the cash equivalent, the employer pays Class 1A National Insurance, and each benefit is valued under its own rules. Cars are valued on list price and CO2 emissions, beneficial loans on the official rate of interest, and many other benefits on the cost to the employer. Some items are exempt — for example certain trivial benefits and qualifying workplace pension contributions — and knowing the exemptions is as much part of the job as knowing what is taxable. HMRC’s expenses and benefits A to Z sets out the treatment item by item.

P11D, P11D(b) and Class 1A

Where benefits are not payrolled, the employer reports them after the tax year on form P11D for each employee and on the P11D(b) return, which also declares the Class 1A National Insurance due. Both are due by 6 July, employees must receive a copy of their P11D information by the same date, and the Class 1A payment must reach HMRC by 22 July if paid electronically (19 July by cheque). Employers who already payroll all their benefits still file a P11D(b) to report Class 1A. The Class 1A rate is 15%, in line with the employer’s secondary Class 1 rate since April 2025, as confirmed in HMRC’s rates and thresholds for employers. The full timetable is on GOV.UK’s guide to reporting expenses and benefits.

Mandatory payrolling from April 2027

The biggest change in this area is the move from year-end P11Ds to real-time reporting through payroll software. The government delayed the original April 2026 start, and HMRC’s interim guidance on mandatory payrolling now sets out a phased introduction. Phase 1 applies from 6 April 2027 to company cars, car fuel, vans, van fuel and private medical benefits. The remaining benefits are due to follow from 6 April 2028, and employers can register to payroll other benefits, including beneficial loans and accommodation, voluntarily from April 2027. Class 1A on payrolled benefits will also be collected in real time rather than once a year. Employers will be able to exclude globally mobile employees and continue to report them on P11D.

In practice this moves the work forward: benefit data must be accurate every pay period, not reconstructed in June, so HR, fleet, providers and payroll need agreed data flows and a clear owner. HMRC is still refining the detail, so check the current guidance before finalising processes.

Off-Payroll Working and IR35

The off-payroll working rules, commonly called IR35, deal with a worker who provides services through an intermediary, usually their own personal service company, in circumstances where they would be an employee if engaged directly. The aim is that the worker pays broadly the same income tax and National Insurance as an employee would. The question underneath is employment status, which turns on factors such as control, substitution, mutuality of obligation and how far the worker is part of the client’s organisation. Those factors often point in different directions, which is why status is one of the hardest judgements in employment tax.

Who decides status

Responsibility depends on the client. All public sector bodies, and private and voluntary sector clients that are medium or large, must decide status themselves. A private sector company is medium or large for these purposes if it meets two or more of the size conditions on turnover, balance sheet total and headcount (more than 50 employees), and a medium or large parent brings its subsidiaries into the rules. Small private sector clients do not make the decision; it stays with the worker’s own company, although the client must confirm its size if asked. HMRC’s guidance on off-payroll working for clients sets out the current tests.

Status Determination Statements and CEST

Where the client is responsible, it must take reasonable care in reaching its decision and issue a Status Determination Statement (SDS) giving the conclusion and the reasons, to the worker and to the next party in the contractual chain. The client must also have a process for the worker to disagree and respond to that challenge. If the engagement is inside the rules, the fee-payer — the party that pays the worker’s company, often an agency — becomes the deemed employer and must deduct income tax and employee National Insurance and pay employer’s National Insurance. If the chain breaks down, liability can pass up to the client.

HMRC’s Check Employment Status for Tax (CEST) tool is the usual starting point. HMRC says it will stand by a CEST result if the information entered is accurate and the tool is used in line with its guidance. It is not a substitute for judgement, though: a CEST printout based on the contract rather than the working reality, or one never revisited when the role changes, gives little protection. Keep the evidence behind each determination and take specialist advice on borderline cases. HMRC’s overview, understanding off-payroll working (IR35), is the reference for the rules as they currently stand.

Umbrella companies from April 2026

A related change took effect for payments made on or after 6 April 2026. Where an umbrella company employs workers supplied to an end client, the agency that contracts with the end client — or the end client itself if no agency is involved — is now responsible for making sure PAYE is operated correctly, and HMRC can recover any underpaid PAYE and National Insurance from it. The umbrella still runs the payroll, but the commercial risk of a non-compliant umbrella has moved up the chain. HMRC’s guidance on PAYE rules for labour supply chains that include umbrella companies explains who is caught and the exceptions, which include workers within the off-payroll rules. Businesses that use temporary labour should review their supply chains, contract terms and due diligence on umbrella providers. Our comparison of temporary employment and fixed-term contracts covers the wider resourcing choice.

Employment-Related Securities, PSAs and Expenses

Employment-related securities

Shares and options acquired because of employment are employment-related securities. Tax-advantaged schemes such as EMI, CSOP, SAYE and SIP each have their own conditions and notification rules, while unapproved awards can create income tax and National Insurance charges — sometimes through PAYE where the shares are readily convertible assets. Employers must register schemes and arrangements with HMRC and file an annual ERS return online by 6 July after the tax year, including nil returns where a scheme is registered but nothing happened. Missed returns attract automatic penalties, and missed EMI or CSOP conditions can cost employees the tax advantage altogether. HMRC’s guide to how employment-related securities work for employers is the starting point.

PAYE Settlement Agreements

A PAYE Settlement Agreement lets the employer settle, in one annual payment, the tax and National Insurance on minor, irregular or impracticable expenses and benefits — staff entertainment, small gifts or occasional travel, for example. Items in a PSA are kept off P11Ds and out of payroll, and the employer pays Class 1B National Insurance on them instead of Class 1A. The tax is grossed up, because the employer is meeting the employee’s liability. A PSA must be applied for by 5 July following the first tax year it covers, and the tax and National Insurance are due by 22 October after the tax year (19 October by post). A PSA is a convenience, not a loophole: regular contractual benefits do not belong in it.

Expenses

Since April 2016, qualifying business expenses that would be deductible for the employee — business travel, subsistence on qualifying journeys, professional subscriptions on HMRC’s approved list — can be reimbursed without reporting, provided the business has checks in place. The risk lies in what falls outside: home-to-office travel, round-sum allowances, temporary workplace claims that are really a permanent workplace, and mileage paid above the approved rates. A clear expenses policy, approvals that actually check the claim, and periodic sample testing are the controls that matter.

The Practical Challenges of Managing Employment Taxes

The first challenge is breadth. Pay, benefits, expenses, contractors, umbrella workers and share awards each have their own rules, deadlines and owners, and the business has to apply all of them correctly across every engagement. The second is the pace of change: rates, thresholds and reporting requirements move most years, and the next two years bring mandatory payrolling and the bedding-in of the umbrella rules. The third is volume. PAYE runs every pay period, so an error in a tax code, a pay element’s NIC treatment or a benefit’s value repeats until it is found.

Status assessment is a further challenge, because it is genuinely difficult and the consequences are significant. So is completeness. Benefits arranged by HR, contractors engaged by operational managers and share awards agreed by the board can all bypass the finance function, and employment tax that nobody identifies is not handled at all.

Where Employment Tax Goes Wrong

The common errors are recognisable, which makes them avoidable:

• Benefits missed or misvalued. A car allowance treated as a car, a director’s loan above the exemption threshold that nobody reported, medical cover added mid-year without a P11D entry.
• Status decisions without evidence. Blanket “outside IR35” decisions, no SDS issued, no disagreement process, or a determination never revisited after the role changed.
• Umbrella supply chains not checked. Since April 2026, an agency or end client that ignores how its umbrella providers pay workers carries the PAYE risk.
• PAYE operated incorrectly. Wrong codes, pay elements given the wrong National Insurance treatment, termination payments taxed incorrectly, or late RTI submissions.
• Share awards not reported. Unregistered arrangements, missed ERS returns, or EMI options granted without the required notification.
• Out-of-date rules. Last year’s rates or thresholds applied to this year’s payroll.

Each exposes the business to tax, interest and penalties, and HMRC’s employer compliance reviews often look back several years. Where an error is found, a voluntary disclosure before HMRC raises it usually produces a better outcome on penalties. Corporation tax sits alongside all of this; our guide to in-house corporation tax compliance covers the wider compliance calendar, and our guide to managing external tax advisers explains how to get specialist support on difficult status cases without losing control of the position.

Building Robust Employment Tax Processes

Because these obligations are recurring and operational, managing them well depends on process rather than ad hoc effort. A sound framework usually includes:

• A payroll calendar covering RTI, the 22nd-of-the-month payment, P60s by 31 May, P11D, P11D(b) and ERS returns by 6 July, Class 1A by 22 July and PSA payment by 22 October.
• A benefits register fed by HR, fleet and providers, reconciled to payroll and ready for real-time reporting from April 2027.
• An off-payroll engagement process: procurement cannot engage a contractor until a status determination is made, recorded and issued.
• Due diligence on agencies and umbrella providers, with contractual rights to the payroll information you need.
• A share scheme register and an annual check of ERS filings and EMI or CSOP conditions.
• An annual review of rates, thresholds and HMRC guidance before the new tax year starts.

These controls belong in the wider control framework; our guide to internal controls for growing businesses covers how to embed them. The ownership question matters too. In smaller businesses the Financial Controller usually holds employment tax with payroll and an external adviser. As headcount, contractor use and benefits grow, many businesses appoint an in-house Tax Manager or, in larger groups, an employment tax specialist. Our guide to hiring your first in-house Tax Manager covers that decision, and the in-house Tax Manager salary guide shows what employment tax specialists typically earn. For a short-term project, such as preparing for payrolling or clearing an IR35 review, see our interim tax day rates.

Frequently Asked Questions

Does IR35 apply to small private companies?

A small private sector client does not decide status; the worker’s own company does. The client must confirm its size if asked. Medium and large clients, and all public sector bodies, must decide status and issue a Status Determination Statement.

What is the Class 1A National Insurance rate?

15%, the same as the main employer’s secondary Class 1 rate since April 2025. It is reported on the P11D(b) by 6 July and paid by 22 July if paid electronically.

When does payrolling benefits in kind become mandatory?

From 6 April 2027 for company cars, car fuel, vans, van fuel and private medical benefits, with remaining benefits due from 6 April 2028. Other benefits can be payrolled voluntarily from April 2027. Check HMRC’s current guidance, as the detail is still being finalised.

Who is liable if an umbrella company underpays PAYE?

For payments from 6 April 2026, the agency contracting with the end client, or the end client where there is no agency, is responsible for making sure PAYE is operated correctly, and HMRC can recover underpayments from it.