IR35 Rules Explained for Side-Hustle Consultants and Freelancers

IR35 rules determine whether a self-employed consultant or freelancer should be treated as an employee for tax purposes when working through an intermediary such as a limited company. For side-hustle consultants and freelancers in the UK, getting this wrong can lead to unexpected tax liabilities and administrative burdens.

This guide explains the key concepts of off-payroll working, how to determine employment status, the small company exemption and what records you must keep. It provides practical steps that early-stage founders and e-commerce sellers can apply when offering freelance services alongside their main business.

What is IR35 and Off-Payroll Working?

IR35 is tax legislation designed to prevent disguised employment. It applies when an individual supplies services to a client through an intermediary, typically a personal service company (PSC). Under off-payroll working rules, the responsibility for determining whether IR35 applies has shifted in many cases from the contractor to the client or agency.

If IR35 applies, the fees paid are treated as employment income. Income tax and National Insurance contributions must be deducted at source. For side-hustlers balancing a day job or growing an e-commerce business, understanding when these rules are triggered helps avoid surprises when invoicing clients.

The rules distinguish between contracts for services (genuine self-employment) and contracts of service (disguised employment). Factors such as control, substitution, mutuality of obligation and financial risk are considered when deciding status.

Determining Employment Status Under IR35

Status determination involves assessing whether the working relationship would be one of employment if the intermediary were removed. You should review the actual working practices, not just the written contract.

Key factors to consider include:

Control: Does the client direct how, when and where the work is done?
Substitution: Can you send someone else to do the work?
Financial risk: Do you bear the cost of mistakes or invest in your own equipment?
Mutuality of obligation: Is the client obliged to offer work and are you obliged to accept it?
Integration: Are you embedded in the client’s organisation like an employee?

Practical step: Use the HMRC Check Employment Status for Tax (CEST) tool as a starting point. Answer every question based on the real terms of each engagement. Keep a screenshot or PDF of the result for your records. If the tool gives an inconclusive outcome, gather additional evidence such as emails showing negotiation of terms or proof of multiple clients.

Review status for every new contract. A side-hustle consultant who sets their own hours, uses their own laptop and works for several different e-commerce businesses is more likely to fall outside IR35 than one who works fixed hours at the client’s premises under close supervision.

The Small Company Exemption

When the end client is a small company, the responsibility for deciding IR35 status usually remains with the contractor rather than the client. This exemption can simplify compliance for many side-hustlers.

A company is considered small if it meets at least two of the following: annual turnover below a certain threshold, balance sheet total below a certain threshold, or fewer than a set number of employees. These thresholds change periodically, so always check the latest definitions on GOV.UK before relying on the exemption.

Practical example: An e-commerce seller hires you to improve their Shopify store for three months. If the seller’s company meets the small company criteria, you as the contractor determine your own IR35 status. You must still reach a reasonable conclusion and keep evidence of how you arrived at it.

If the client is a medium or large organisation, or a public sector body, they must determine status and issue a Status Determination Statement (SDS). You should receive this before work begins and can challenge it if you disagree.

Record Keeping Requirements

HMRC expects clear evidence that you have considered IR35 properly. Maintain a dedicated folder for each contract containing the following:

Copy of the contract and any variations
CEST results or your own reasoned assessment
Correspondence showing how terms were negotiated
Evidence of actual working practices (timesheets, emails, invoices)
Status Determination Statement if received from the client

Keep these records for at least six years. If you operate through a limited company, store them alongside your company accounts and corporation tax filings. For sole traders, keep them with self-assessment records.

Practical tip: Create a simple IR35 checklist you complete at the start of every new engagement. Note the client size, who is responsible for the determination, the main reasons you believe the contract is outside IR35, and any steps taken to reinforce self-employed status such as using your own branding or advertising availability to other clients.

Practical Steps for Side-Hustle Consultants

1. Decide on your trading structure early. Operating as a limited company gives more flexibility but brings additional IR35 responsibilities. Sole trader status is simpler but offers less protection. Thresholds and rules change, so review the latest guidance on GOV.UK and Companies House.

2. Draft contracts that reflect genuine self-employment. Include clauses on the right to substitute, payment on completion of deliverables rather than time spent, and no exclusivity.

3. Market your services to multiple clients. A varied client base strengthens the case for self-employment. An e-commerce side-hustler who helps several independent Shopify stores is in a stronger position than one reliant on a single retailer.

4. Invoice for the work, not time. Present fees as project costs or day rates with clear deliverables. Avoid language that sounds like salary.

5. Consider insurance. Professional indemnity and public liability policies can support your self-employed status and protect your business. Check current requirements with an insurer.

Common Pitfalls and How to Avoid Them

Many side-hustlers fall into IR35 difficulties by using templated contracts that do not match reality. If you work set hours at the client’s office using their equipment while they direct your daily tasks, the contract wording alone will not protect you.

Another risk is failing to obtain or keep a Status Determination Statement. If the client is required to provide one and does not, you should ask for it in writing. If you disagree with the SDS, use the client’s dispute process promptly and document every step.

Finally, do not ignore the rules because your side-hustle is small. HMRC can still investigate and recover tax, interest and penalties. Regular review of your contracts and working practices is the safest approach.

Seeking Support as an Early-Stage Founder

Running a side hustle alongside an e-commerce business or startup brings many administrative demands. Places such as Loomworks in West Yorkshire can offer practical mentoring and a registered address to selected founders, helping reduce overheads while you focus on compliance and growth.

Stay informed by regularly checking official sources. Rules around off-payroll working, company size and record keeping evolve, so verify the latest position directly with HMRC and GOV.UK before making decisions on new contracts.

Frequently asked questions

Who is responsible for determining IR35 status?

It depends on the size of the client. Small companies leave the decision with the contractor. Medium and large private sector clients, and all public sector bodies, must determine status and issue a Status Determination Statement. Always confirm the client’s size using the latest criteria on GOV.UK.

Can I still operate my side hustle if IR35 applies?

Yes. You can continue to trade but the engagement will be taxed as employment. The client or agency deducts tax and National Insurance before paying your limited company. You may still claim some expenses, but the overall tax position changes. Many consultants adjust their rates to reflect this.

What records do I need to keep for IR35?

Keep contracts, CEST results or your own status assessment, evidence of working practices, any Status Determination Statements and related correspondence. Retain everything for at least six years. Organise records by contract so you can demonstrate reasonable care if HMRC enquires.

Does the small company exemption apply to all my clients?

Only to those that meet at least two of the small company criteria. You must check each client individually. If a client grows beyond the thresholds during your contract, the rules may change part way through. Document the size at the start of each engagement.

How often should I review my IR35 position?

Review every new contract and whenever working practices change significantly. A quick check at the start of each engagement helps avoid problems. Annual reviews of all active clients are also sensible for anyone running a regular side hustle.