Self-employed personal trainer in the UK: how to register with HMRC

Are you self-employed?

GOV.UK says you are probably running a business if, among other things, you:

• take responsibility for its success or failure
• have several customers at the same time
• can decide how, where and when you do your work
• provide the main items of equipment to do your work
• charge an agreed fixed price for your work

For personal trainers, that often describes anyone who finds their own clients, sets their own prices and rents space in a gym or trains clients at home or outdoors. If a gym pays you a wage through PAYE, you are an employee for that work.

You can be both. GOV.UK says you can run a business and be employed at the same time, for example working for an employer during the day and running your own business in the evenings. Employment status can be complicated, and HMRC may treat someone as self-employed for tax even if their status in employment law is different. If you are not sure, contact HMRC.

Being a sole trader

A sole trader is the simplest business structure to set up and keep records for. As a sole trader you work for yourself, you are classed as self-employed and you make all the business decisions. You keep all the profits after paying tax.

Sole traders have unlimited liability, which means you are personally responsible for all the debts of the business. GOV.UK suggests business insurance may give you more protection. You can trade under your own name or choose a trading name.

There are other ways to set up a business, such as a limited company. GOV.UK notes that if you run a limited company you are not self-employed, even if you are the owner and only employee, and different rules apply. This guide covers sole traders.

When you must register

GOV.UK says you must register as a sole trader if you:

• earn more than £1,000 in a tax year (from 6 April to 5 April)
• need to prove you are self-employed, for example to claim Tax-Free Childcare
• want to make voluntary Class 2 National Insurance payments to help you qualify for benefits and State Pension

You register as a sole trader by registering for Self Assessment. You can choose to register earlier than you need to.

The registration deadline is 5 October after the end of the tax year. For example, the 2025 to 2026 tax year ended on 5 April 2026, so the deadline to tell HMRC was 5 October 2026. If you start in the 2026 to 2027 tax year and earn more than £1,000, register by 5 October 2027. If you register late or do not register when you need to, you may get a penalty.

If you register after 5 October, HMRC will send you a letter or email with a different deadline for your tax return, 3 months from the date on it. You must still pay what you owe by the normal payment deadline.

If you are already registered for Self Assessment for another reason, GOV.UK says you need to register again as a sole trader, so you are registered for Class 2 National Insurance.

How to register, step by step

1. 1Have your National Insurance number ready. You need one to register. You can apply for one if you do not have it.
2. 2Use the GOV.UK service. Search GOV.UK for "Register as a sole trader" (gov.uk/become-sole-trader/register-sole-trader) and follow the steps. How you register depends on your circumstances.
3. 3Wait for your Unique Taxpayer Reference (UTR). You need it to file your tax return. GOV.UK has a tool to check when you can expect a reply from HMRC.
4. 4Set up your records from your first day of trading (see below).
5. 5File your return and pay by the deadlines below.

Records to keep

GOV.UK says sole traders must keep records of business income and expenses for their Self Assessment tax return, and records of personal income too.

For a personal trainer, that typically means:

• every session and package payment, whether by card or cash
• card payouts from your payment provider
• receipts for business costs such as gym rent, insurance, equipment, travel and courses

From the 2024 to 2025 tax year, cash basis is the default accounting method. With cash basis you record income when you receive the money and expenses when you pay the bill. You can opt out and use traditional accounting instead.

Expenses and the £1,000 trading allowance

You can deduct allowable expenses from your income to work out your taxable profit. GOV.UK's examples include:

• travel costs, such as fuel, parking, train or bus fares
• clothing expenses, such as uniforms
• financial costs, such as insurance or bank charges
• costs of business premises, such as heating, lighting and business rates
• advertising or marketing, such as website costs
• training courses related to your business, such as refresher courses

If you use something for both business and personal reasons, you can only claim the business part. If you are not sure whether a cost is allowable, contact HMRC.

The trading allowance. You can get up to £1,000 a year tax-free from trading. If your gross trading income is £1,000 or less, you may not need to tell HMRC. If it is more, you can deduct the £1,000 allowance instead of your actual expenses, but not both.

Income Tax and National Insurance (2026 to 2027)

This is general information, not tax advice. HMRC works out what you owe from your profits when you submit your tax return. These GOV.UK figures apply to the 2026 to 2027 tax year (6 April 2026 to 5 April 2027).

Income Tax bands are different if you live in Scotland. Your Personal Allowance goes down by £1 for every £2 of adjusted net income over £100,000, so it is zero at £125,140 or above. Most people pay Class 2 and Class 4 National Insurance through Self Assessment.

Key deadlines

For the 2025 to 2026 tax year (6 April 2025 to 5 April 2026):

Payments on account are advance payments towards your next tax bill, including Class 4 National Insurance. Each is usually half of the tax you owed last year, due by 31 January and 31 July. You do not have to make them if the tax you owed last year was less than £1,000, or if you paid more than 80% of it outside Self Assessment.

Making Tax Digital for Income Tax

Sole traders registered for Self Assessment will need to use Making Tax Digital for Income Tax once their qualifying income passes a threshold. GOV.UK says that if your qualifying income is over:

• £50,000 for the 2024 to 2025 tax year, you should have started from 6 April 2026
• £30,000 for the 2025 to 2026 tax year, you will need to use it from 6 April 2027
• £20,000 for the 2026 to 2027 tax year, you will need to use it from 6 April 2028

HMRC checks your qualifying income from your tax return each year. GOV.UK has a tool to check if and when you need to use it.

VAT

You must register for VAT if your total taxable turnover for the last 12 months goes over £90,000, or you expect it to go over £90,000 in the next 30 days. You can choose to register voluntarily below that. If you might reach the threshold, plan your prices with VAT in mind.

Other things to sort out

• Insurance. GOV.UK lists business insurance among the things to check. See what insurance a personal trainer needs.
• Background checks. The National Careers Service says personal trainers need to pass enhanced background checks, because they may work with children and vulnerable adults.
• Data protection. The ICO says sole traders who use personal information must pay a data protection fee unless they are exempt. See GDPR for personal trainers.
• First aid. The National Careers Service says it is usual to hold a first aid certificate that includes CPR.

Where FitDesk fits in

FitDesk is not accounting or tax software. It does not work out your tax and it does not file tax returns. What it does is help you schedule sessions, manage clients, take Stripe card payments and record cash payments. With your bookings, Stripe card payments and recorded cash payments in one place, it can be easier to gather your income records at the end of the year.

No monthly fee. 0.7% on Stripe card payments through FitDesk, minimum 1p per card payment. Stripe's own fees still apply. Cash has no FitDesk fee.

Sources

• GOV.UK, Working for yourself: gov.uk/working-for-yourself (checked 7 October 2026)
• GOV.UK, Become a sole trader: gov.uk/become-sole-trader (checked 7 October 2026)
• GOV.UK, Register as a sole trader: gov.uk/become-sole-trader/register-sole-trader (checked 7 October 2026)
• GOV.UK, Check how to register for Self Assessment: gov.uk/register-for-self-assessment (checked 7 October 2026)
• GOV.UK, Self Assessment tax returns, who must send a tax return: gov.uk/self-assessment-tax-returns/who-must-send-a-tax-return (checked 7 October 2026)
• GOV.UK, Self Assessment tax returns, deadlines: gov.uk/self-assessment-tax-returns/deadlines (checked 7 October 2026)
• GOV.UK, Understand your Self Assessment tax bill, payments on account: gov.uk/understand-self-assessment-bill/payments-on-account (checked 7 October 2026)
• GOV.UK, Employment status, self-employed and contractor: gov.uk/employment-status/selfemployed-contractor (checked 7 October 2026)
• GOV.UK, Business records if you're self-employed: gov.uk/self-employed-records (checked 7 October 2026)
• GOV.UK, Expenses if you're self-employed: gov.uk/expenses-if-youre-self-employed (checked 7 October 2026)
• GOV.UK, Tax-free allowances on property and trading income: gov.uk/guidance/tax-free-allowances-on-property-and-trading-income (checked 7 October 2026)
• GOV.UK, Income Tax rates and Personal Allowances: gov.uk/income-tax-rates (checked 7 October 2026)
• GOV.UK, Self-employed National Insurance rates: gov.uk/self-employed-national-insurance-rates (checked 7 October 2026)
• GOV.UK, Find out if and when you need to use Making Tax Digital for Income Tax: gov.uk/guidance/find-out-if-and-when-you-need-to-use-making-tax-digital-for-income-tax (checked 7 October 2026)
• GOV.UK, Register for VAT: gov.uk/register-for-vat (checked 7 October 2026)
• National Careers Service, personal trainer job profile: nationalcareers.service.gov.uk/job-profiles/personal-trainer (checked 7 October 2026)