How does HMRC determine if a worker is employed or self-employed?

HMRC determines whether a worker is employed or self-employed by examining the actual working relationship against a range of factors, primarily control, substitution and financial risk. No single factor is decisive; the overall picture must be considered.

Getting the classification right matters for tax, National Insurance and administrative obligations. This guide explains the main tests, how to use the official CEST tool and practical steps you can take to assess your own arrangements accurately.

Why employment status matters for startups and e-commerce sellers

Early-stage founders and online sellers often work with freelancers, contractors or part-time helpers. Misclassifying a worker as self-employed when they are actually employed can lead to unexpected liabilities for income tax, National Insurance contributions and potential penalties. Equally, treating someone as employed when they operate genuinely on their own account creates unnecessary administrative burden.

Status affects whether you must operate PAYE, pay employer National Insurance, provide holiday pay or meet other employment rights. Because rules change, always check the latest guidance on GOV.UK before making decisions.

The CEST tool – your starting point

HMRC provides the Check Employment Status for Tax (CEST) tool on GOV.UK. It asks a series of questions about the specific engagement and gives an opinion on whether the worker would be treated as employed or self-employed for tax purposes.

Practical steps to use CEST effectively:

• Answer every question based on the actual terms and behaviours, not what you hope or intend.
• Run the check for each distinct piece of work or role rather than assuming one result covers everything.
• Save or print the determination and the answers given as evidence of reasonable care.
• Re-run the test if the working practices change.

The tool cannot give a definitive legal ruling, but following it in good faith helps demonstrate you took reasonable care if HMRC later enquires.

The control test in detail

Control is one of the strongest indicators of employment. HMRC looks at who decides what work is done, how it is done, when it is done and where it is carried out.

Questions to ask yourself:

• Can you or the worker decide which tasks are accepted or refused?
• Does the worker have genuine freedom over working hours and location?
• Is the worker told exactly how to perform the task or simply given an outcome to achieve?
• Is there regular supervision, appraisal or instruction?

Example reasoning: An e-commerce seller asks a freelance photographer to produce product images. The seller provides a detailed shot list, specifies lighting and editing software, requires the work to be done on-site on specific days and reviews every image before payment. This level of control points towards employment. In contrast, if the photographer agrees only the required number of images, chooses their own schedule, equipment and editing style, and delivers files by an agreed deadline, the arrangement leans towards self-employment.

The right of substitution

A genuine right of substitution is a strong indicator of self-employment. This means the worker can send someone else to do the work without your prior approval, provided that person meets the required standard.

Practical checks:

• Is substitution written into the contract and actually possible in practice?
• Does the worker bear the cost of paying the substitute?
• Have substitutes been used before without objection?

If you insist on a named individual, reject substitutes or require personal service every time, the right is not genuine and the arrangement looks more like employment. For example, a virtual assistant who must do all customer service chats themselves and cannot send another qualified person suggests employment. A web developer who can nominate another trusted developer from their network to meet a tight deadline, and who pays that developer directly, demonstrates substitution consistent with self-employment.

Financial risk and the opportunity to profit

Financial risk is the third core test. Self-employed workers typically bear the risk of making a loss, have to fund their own equipment or materials, correct faulty work at their own cost, and can increase profit by working more efficiently or taking on additional clients.

Indicators of genuine financial risk:

• The worker quotes a fixed price for a project and absorbs any extra time or cost.
• They are responsible for their own insurance, marketing and training.
• They can negotiate higher fees for urgent work or choose which jobs to accept.
• Payment is made on completion of agreed deliverables rather than by the hour or day.

Example reasoning: A bookkeeper engaged by an online retailer to prepare quarterly figures is paid a set project fee. If the work takes longer than expected they still receive only the agreed amount and must correct any errors free of charge. They also work for several other clients and can turn down work. These factors indicate self-employment. If the same person is required to work fixed hours each week, is paid regardless of workload, has all equipment provided and cannot work for competitors, the financial risk is low and the relationship looks employed.

Other relevant factors and building the overall picture

Beyond the three main tests, HMRC considers integration into the business, provision of equipment, length of engagement, method of payment and whether the worker is labelled a contractor in writing. Written contracts help but cannot override the reality of how the work is carried out day to day.

Useful record-keeping steps:

1. Keep a written agreement for each contractor that clearly sets out the deliverables, deadlines, payment terms and any right of substitution.
2. Maintain timesheets, emails and project briefs that show the actual degree of control exercised.
3. Record occasions when substitutes were used or when the worker declined work.
4. Review arrangements every six months or when the nature of the work changes.

If the picture is mixed, seek professional advice. Remember that thresholds, rates and detailed rules change; always verify current requirements on GOV.UK or with HMRC.

Common pitfalls for e-commerce and startup teams

Many founders assume that because someone invoices them they must be self-employed. HMRC looks past the invoice to the reality. Regular, exclusive work for one business, using company equipment, attending team meetings and following company processes can all point towards employment even if the worker describes themselves as freelance.

Another pitfall is long-term contractors who gradually become integral to daily operations. An e-commerce operations manager who has worked exclusively for you for two years, works set hours and follows your processes may be viewed as disguised employment. Regularly testing such relationships with the CEST tool and adjusting terms where needed helps protect both parties.

Frequently asked questions

Related reading: Can UK businesses reclaim VAT paid in other countries?, Essential finance terms every new UK founder should know, How has R&D tax credit intensity threshold changed?. Browse all tax & finance guides or apply to Loomworks.