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UK companies: Tax Identification Numbers (TINs)

Tax Identification Numbers (TINs)

Tax Identification Numbers (TINs) come in all shapes and sizes and are used worldwide by companies, individuals and governments for tax administration. They can differ slightly in each country however, TINs are essentially used for the same reason the world over – gathering tax and ensuring compliance with tax laws, whether that’s in one specific country or across borders.

Firstly, a TIN is a unique combination of letters and/or numbers allocated to an individual or a company by its local tax administration authority used for the identification of the taxpayer. Let us look at some examples of UK TINs and how and where they will be used in business.

Although in the UK the term TIN is not commonly used as much as it is overseas, we still have various numbers which would fall under the general description of a TIN. Anyone in business dealings with foreign authorities or overseas businesses is likely to find the acronym TIN used, and may find themselves being asked to supply their TINs in order to carry out business.


Individual TINs.

There are two main numbers used to identify individual UK taxpayers.

  • National Insurance number (NI)
  • Unique Taxpayer Reference (UTR)

National Insurance number 

A national insurance number, made up of 2 letters, 6 numbers, followed by a letter, is allocated to all UK individuals a few months before their 16th birthday; children aged under 16 are not liable to pay national insurance contributions in the UK, although they can still be liable to pay other taxes.

A National Insurance number is used throughout an individual’s lifetime by various organisations for tax purposes including:

  • His Majesty’s Revenue and Customs (HMRC), UK tax office.
  • Employers, as part of the UK PAYE system.
  • Department of Work and Pensions along with other private pension providers.
  • Local councils, including Electoral Registration Officers
  • Student Loans Company
  • Financial service Providers, for investments like shares, bonds and ISAs.

Where can I find my NI number? 

A national insurance number can always be found by logging into your personal tax account, or it will be on your payslip, P60, and on any official tax paperwork; pensions, benefits or HMRC letters.

Can anyone get a National Insurance number? 

The individual will need to live in the UK to apply.

They must have the right to work in the UK.

And one of the following:

  • A British passport.
  • A valid visa or a biometric residence permit.
  • A settled or pre-settled status, under the EU Settlement scheme

To apply for an NI number, see apply NI number.

Unique Taxpayer Reference (UTR) for Individuals.

Important note: Both Limited Companies and Individuals can have UTR numbers, they are unique to either the company or the individual.

A unique taxpayer reference number for an individual person is allocated by HMRC when a person registers to file self-assessment tax returns. This may be as a sole trader, as a director or for filing for various benefits. This UTR number is linked to an individual’s NI number and once applied for the UTR stays with a person for life, even if they do not always need to file self-assessment tax returns.

If you need to retrieve a UTR number from previous self-assessments, you can find it by logging into your personal tax account

If you need to register for self-assessment as a sole trader, Duport can help see sole trader registration


Company Tax Identification numbers (TINs)

In the UK, two main identification numbers are used concerning limited companies.

  • Unique Taxpayer Reference (UTR)
  • Company Registration number (CRN)

Every UK company will have both numbers allocated to them, but they are used for slightly different purposes during business administration which is why they both will fall under the general remit of a Tax Identification Number (TIN).

Unique Taxpayer Reference – Limited Company.

When a new company is incorporated in the UK HMRC will be automatically notified and will allocate the new company a 10-digit UTR number. This will be posted to the Registered Office address of the new company within 1 month of registration. After this point, it can be found on all correspondence sent from HMRC and is available by logging into the company’s online Corporation Tax account.

Using a company UTR: you will need to reference your company UTR in the following situations.

  • Tax Compliance:
  • Filing and paying corporation tax returns, registering, filing and paying VAT returns.
  • Hiring Employees
  • registering for PAYE (pay as you earn) and in the payment of employees.
  • International Transactions:
  • TINs are often required for international transactions and dealings with foreign tax authorities.
  • correspondence with HMRC
  • Informing HMRC that a company has become dormant, changing a Corporation Tax accounting period, informing HMRC of changes to a business.

Company Registration number (CRN)

A company registration number is issued by Companies House on the incorporation of a limited company. It is a unique sequence of 8 characters of either 8 numbers or 2 letters followed by 6 numbers. A CRN can be found on the company’s Incorporation Certificate, on all correspondence from Companies House and is visible on the public Company register on Companies House website.

Using a CRN: you will need to reference your CRN in the following situations.

  • Updating company details; including updates to Registered Office address, company name, changes, or updates to company officers (directors, PSCs etc.).
  • Online filing with Companies House; used as an identifier in both Confirmation Statement filing and Annual Accounts filing.
  • Filing with HMRC, including Corporation Tax filing, VAT & PAYE registration & filing.
  • Shares, CRN is used when filing a Return of Allotment of Shares or when issuing share certificates.
  • Bank accounts & financial institutions will need the CRN to open a bank account or provide credit searches.
  • Business stationery: By law, the CRN needs to be displayed on all company stationaries; this includes all invoices, letterheads, websites, emails and marketing information.

In the UK there are principally 4 common types of TINs. Individuals have National Insurance numbers and a Unique Taxpayer Reference number, once they register for Self-Assessment tax returns. Limited companies are given a Company Registration Number by Companies House and a Unique Taxpayer Reference number allocated by HMRC. Hopefully, you now understand the principal reason for the use of Tax Identification Numbers (TINs) and how they work in conjunction to create a tax identification system unique to each person or limited company.


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