If you are self-employed, a company director, a landlord, or have any income that needs to be declared to HMRC outside of PAYE employment, you will need a UTR number UK Your Unique Taxpayer Reference is one of the most critical pieces of tax identification in the UK — yet thousands of people remain uncertain about what it actually is, how to obtain one, and exactly when to use it. This comprehensive AccoFirm guide answers every question about UTR numbers in the UKso you can stay compliant and avoid costly penalties.
What Is a UTR Number?
A UTR (Unique Taxpayer Reference) is a 10-digit number issued by HMRC to identify individuals and businesses for tax purposes. What makes it particularly significant is its permanence — your UTR is unique to you and remains the same throughout your life. You will never be assigned a different one, even if you stop being self-employed and start again years later.
Every time you interact with HMRC’s Self Assessment system, your UTR number is required. Think of it as your personal tax identification number for self-employment and any other income that falls outside the PAYE system. Without it, you simply cannot complete or submit a tax return.
Who Needs a UTR Number in the UK?
Many people are surprised to discover they need a UTR number. You will require one if any of the following circumstances apply to you:
- You are self-employed as a sole trader or freelancer
- You are a partner in a business partnership
- You are a limited company director receiving a salary and/or dividends
- You earn rental income from a UK property
- You have income from savings, investments, or capital gains that exceed HMRC’s reporting thresholds
- You receive income from abroad
- Your total income from all sources exceeds £100,000 per year
- You have untaxed income from any source over £2,500 per year
- You receive Child Benefit and your household income exceeds £50,000 (High Income Child Benefit Charge)
- You are a trustee of a trust
- HMRC has sent you a notice to file a Self Assessment tax return
If even one of these situations applies to you, registering for a UTR number is not optional — it is a legal obligation.
What Does a UTR Number Look Like?
A UTR number is exactly 10 digits long and contains no letters whatsoever. On official HMRC correspondence, it may appear with a space between the first three and last seven digits — for example: 123 4567890. However, when entering your UTR on digital forms or HMRC systems, you should input all 10 digits as a continuous string, without any spaces.
It is important not to confuse your UTR with other HMRC reference numbers:
- National Insurance Number (NI Number): Formatted as two letters, six digits, and one letter — e.g., QQ 12 34 56 A. Used across PAYE employment and benefits, not for Self Assessment.
- Company Registration Number (CRN): An 8-digit reference issued by Companies House to limited companies — entirely separate from tax affairs.
- VAT Registration Number: A different reference used solely for VAT purposes and not interchangeable with your UTR.
How to Get a UTR Number in the UK
Obtaining a UTR number requires registering for Self Assessment with HMRC. The exact process varies slightly depending on your specific circumstances.
For Self-Employed Individuals (Sole Traders)
You must register for Self Assessment by 5 October following the end of your first tax year of self-employment. For instance, if you began trading in July 2025, your registration deadline is 5 October 2026.
Here is the step-by-step registration process:
Step 1: Create a Government Gateway account at gov.uk/register-for-self-assessment if you do not already have one.
Step 2: Complete the SA1 or CWF1 form online. The CWF1 is specifically designed for those who are newly self-employed.
Step 3: HMRC will issue your UTR number by post within 10 working days (or up to 21 days for overseas addresses).
Step 4: Activate your Self Assessment online account using the separate activation code that HMRC sends by post.
For Company Directors
When you register a limited company with Companies House, HMRC is automatically notified and will issue a UTR to the company itself. However, as a director, you also need a personal UTR for your own Self Assessment tax return. If you do not already have one, you must register separately using form SA1.
For Landlords
If your rental income requires Self Assessment reporting, register using form SA1. If you are already in PAYE employment and additionally earning rental income, contact HMRC directly — they may be able to collect smaller amounts through an adjusted PAYE tax code, potentially eliminating the need for a full Self Assessment return.
Where to Find Your UTR Number
Already have a UTR but cannot remember where you stored it? Here are all the places it could be:
- HMRC correspondence: Any official letter, notice, or tax return sent by HMRC will display your UTR prominently at the top of the document.
- Self Assessment tax return: Your UTR appears in the header section of the SA100 form.
- Your HMRC Personal Tax Account: Log in at gov.uk, navigate to the Self Assessment section, and your UTR will be displayed there.
- The HMRC app: Available on both the App Store and Google Play, the app shows your UTR within your personal details section.
- Your accountant: If you work with a professional accountant or tax agent, they will have your UTR securely on file.
If none of the above work and you genuinely cannot locate your UTR, call HMRC’s Self Assessment helpline on 0300 200 3310 (available Monday to Friday, 8am to 6pm). You will be required to verify your identity before HMRC will confirm the number.
What Is a CIS UTR Number?
Within the Construction Industry Scheme (CIS), both contractors and subcontractors hold their own UTR numbers. If you are a subcontractor in the construction sector and are registered for CIS, your UTR is used by contractors to verify your CIS status with HMRC before making any payments to you.
The outcome of that verification determines the tax deduction rate applied to your earnings:
- 20% deduction for registered subcontractors
- 30% deduction for unregistered subcontractors
CIS UTR numbers follow exactly the same format as all other UTR numbers — 10 digits — and are obtained through the same Self Assessment registration process. The key distinction is that CIS registration is a separate process from basic Self Assessment registration and must be completed independently.
Company UTR vs Personal UTR: What Is the Difference?
When you form a limited company, it receives its own 10-digit company UTR — also referred to as a Corporation Tax UTR — which is entirely separate from any personal UTR held by the director. These two references serve distinct purposes and must never be confused:
| Type | Who It Belongs To | Used For |
|---|---|---|
| Personal UTR | An individual person | Self Assessment, personal tax returns, CIS |
| Company UTR | A limited company | Corporation Tax returns, company tax affairs |
Directors must actively maintain both their personal UTR and their company UTR. Submitting an HMRC document with the wrong UTR can cause serious processing delays and may trigger further queries from HMRC.
What Happens If You Don’t Register for a UTR When Required?
Failing to register for Self Assessment by the 5 October deadline is taken seriously by HMRC and carries escalating financial penalties:
- £100 penalty for late filing, applied immediately
- £10 per day after 3 months of continued non-compliance (up to a maximum of £900)
- £300 or 5% of the tax due (whichever is greater) imposed at the 6-month mark — and again at 12 months
- Interest charges applied to any tax that was paid late
- Potential HMRC investigation into whether you have unreported income
Beyond the penalties themselves, HMRC has dramatically expanded its use of data analytics to detect unregistered self-employed individuals. If you earn income from digital platforms such as Uber, Airbnb, Deliveroo, eBay, or Etsy above the £1,000 trading allowance, HMRC is very likely already aware of it. This is due to the Digital Platform Reporting regime, which came into effect in 2026 and requires platforms to report user earnings directly to HMRC.
UTR Numbers for Non-UK Residents
If you are a non-UK resident but hold UK tax obligations — for example, through UK rental income or UK-sourced employment — you can still apply for a UTR number. The process involves completing form SA1 and posting it directly to HMRC. Be aware that processing times are longer for overseas applicants, typically around 21 days.
Alternatively, you can appoint a UK-based accountant or tax agent, such as AccFirm, to register on your behalf. This can significantly simplify the process, particularly if you are unfamiliar with the UK tax system or are managing cross-border tax obligations.
Can Someone Else Use Your UTR Number?
Absolutely not. Your UTR is strictly personal to you and should only ever be shared with your authorised accountant or tax agent. Sharing it with anyone else is a serious security risk that could expose you to identity theft or tax fraud.
Fraudsters are known to request UTR numbers as part of elaborate tax refund scams. It is vital to remember that HMRC will never ask for your UTR via text message, email, or social media. If you receive any unsolicited communication requesting your UTR number, treat it as a potential scam immediately and report it to HMRC’s dedicated phishing team.
Frequently Asked Questions: UTR Number UK
How long does it take to get a UTR number?
HMRC typically issues a UTR number within 10 working days of a completed registration for UK-based applicants. For overseas applicants, allow up to 21 days. Registering online via gov.uk remains the fastest and most efficient method available.
Can I file a tax return without a UTR?
No. A UTR number is a mandatory requirement for filing a Self Assessment tax return — there is no workaround. If you have misplaced yours, contact HMRC on +44 20 3885 6282 to retrieve it well in advance of any filing deadline.
Is a UTR number the same as a tax reference number?
These two terms are frequently used interchangeably, though there is a technical distinction. Your UTR is specifically associated with Self Assessment and personal tax. HMRC also uses other references — such as your Accounts Office Reference and PAYE Reference — which are relevant to employers rather than individuals. Your UTR is the primary reference number for all personal tax matters outside PAYE.
Do I need a UTR if I am employed but also have a side hustle?
Yes, if your side hustle income exceeds £1,000 per year. This is the threshold set by the trading allowance, and any earnings above it require you to register for Self Assessment and obtain a UTR. Income below £1,000 annually from self-employment remains exempt under the trading allowance rules.