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  • Writer's pictureGarrett Stuart

What is a Tax Identification Number (TIN)?

Updated: Mar 20

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A Tax Identification Number (frequently referred to as a TIN) is one of the things that we’re frequently asked about – and depending on whether you’re an individual, or a company owner, it is different. It is different again when we start looking at companies that operate in different territories worldwide!

Here in the UK, there are just a couple of different Tax Identification Numbers that you’ll need to know. These TINs are really important for business owners, sole traders, and anyone who has to submit a tax return, since if you get it wrong, you may end up with a late submission, and HMRC will apply a fine to your account. That can sometimes be sorted out, but spending time on the phone to HMRC when you don’t have to is frustrating – take it from us! Let’s take a look at the Tax Identification Numbers that you need to know.

What is a Tax Identification Number?

A Tax Identification Number is just what it seems like it should describe – and that is, a number that can be used to identify you, or your business, for tax purposes. It is a catch-all phrase that can be applied to several different types of numbers that are used by HMRC, and by tax bodies in other countries.

Most countries have their own types of Tax Identification Number, and if you’re operating even in one other country, it is your responsibility to make sure you register for Tax Identification Numbers for the relevant territories.

What Tax Identification Numbers are used in the UK?

In the UK, taxes are dealt with by His Majesty’s Revenue and Customs (HMRC), and it is HMRC that creates the Tax Identification Numbers for individuals and businesses that operate here. The main types are the Unique Taxpayer Reference (the UTR) and the National Insurance Number (NI number). Each number is individual to the person they have been allocated to, and so they should be treated confidentially, as they are personal information. After HMRC has allocated a National Insurance Number, or Unique Taxpayer Reference, they are fixed and won’t change. They are always formatted in the same way, which can help you to identify which one is which.

Unique Taxpayer Reference (UTR)

This Tax Identification Number is assigned by HMRC either when an individual registers for Self Assessment, or when a limited company is being set up. This code is made up of 10 digits, and you’ll sometimes see or hear it being referred to as a tax reference number.

HMRC don’t issue a card with your UTR on it, but you can find your UTR on most documents that you receive from them. Letters and notices that you will definitely see your UTR noted on include:

· The SA250 letter entitled Welcome to Self Assessment

· The Self Assessment tax return paperwork

· A notice to file a tax return

· A statement of account

· Any payment reminders

If you haven’t received one of these documents, and you’re certain that you don’t have a UTR yet, then you’ll need to go through the process to register for Self Assessment online. To do this, you’ll need:

· Your name, date of birth and address

· Your National Insurance Number

· Your email address and telephone number

· The name, address and nature of your business

· Your business telephone number

· The date your self-employment started

It can take a significant amount of time to get your UTR through, so be sure to register in good time, so that you can receive it well ahead of the date that you need your tax return to be completed. In some cases, it can be longer than a few weeks before the UTR will arrive with you, so don’t put it off. As we’ve already mentioned, missing deadlines can result in expensive fines – and nobody wants one of those.

National Insurance Number (NI number)

The National Insurance Number is the other main number that is used as a Tax Identification Number in the UK. You can recognise the NI number, as it has two letters, followed by six numbers, then one of the letters A, B, C or D. In most cases, National Insurance Numbers are issued automatically when a young person reaches the age of 16, and they will receive a letter, and sometimes a card with their NI number on it.

National Insurance Numbers are issued by the Department for Work and Pensions or HM Revenue and Customs. If you don’t have a National Insurance Number – for example, because you were born in another country – you need to apply for one. By applying for a National Insurance Number, you will be able to work, claim benefits, apply for a student loan or to pay Class 3 voluntary National Insurance contributions.

If you don’t have your National Insurance number to hand, you should be able to see it on any payslips that you have from an employer, and you’ll also see it on a Statement of Account issued by HMRC. Some other documents from HMRC will also show the National Insurance Number, but not all do.

What if I don’t have a UTR or a NI number?

There are occasions when resident taxpayers, or UK nationals don’t have either a UTR or an NI number. If this is the case, you may be issued with a PAYE Temporary Reference Number (TRN), which is made up of two numbers, one letter, then five numbers. This should only be used temporarily, and it is important to get your UTR, and your NI numbers sorted as soon as possible.

Are companies allocated a Tax Identification Number?

Yes, companies can be allocated a Unique Taxpayer Reference, and are usually issued a Corporation Tax number upon registering their company with Companies House. This isn’t the same as a Company Registration Number (CRN) though – so don’t mix them up. Your CRN is issued when the company becomes incorporated (when it becomes its own legal entity). The CRN is made up of a combination of 8 alpha-numeric characters, and is used to identify your company, in case another company has a similar name, but also to verify incorporation with Companies House.

How do I know which Tax Identification Number I need in another country?

Each country worldwide has a different type of Tax Identification Number – and of course, there might be more than one. You might find that you need a social security number, the number from your passport, or an identity card from the country, or there might be another number entirely that you need.

As an example, in the US, the TINs are issued by the federal government, and are used by both individuals and companies for their taxes, which are managed by the Internal Revenue Service (IRS). TINs are issued to individuals by the Social Security Administration, while the IRS allocated TINs to companies.

Other Tax Identification numbers the US use include Social Security Numbers, Individual Taxpayer Identification Numbers (ITIN), Employer Identification Number (EIN), Adoption Taxpayer Identification Number (ATIN), and Preparer Taxpayer Identification Number. Even from state to state, there are different numbers that may be required! In Massachusetts, New York and South Carolina, every business must also have a state tax ID number in addition to their federal tax ID number.

With all this in mind, you can see how complex it can get – and this is just within one country. Because there are different laws and expectations for taxes in countries worldwide, it is really important to get the correct TIN for each country that you pay taxes.

How can I find out which Tax Identification Number I need for different countries?

To find the relevant Tax Identification Number, you can find a list here, but don’t assume this is all you will need. Always do your due diligence and check the website for the relevant tax body in the countries that you’re operating, and if necessary, take advice from a tax professional in the country or countries in which you’re working.

Our final thoughts

In theory, Tax Identification Numbers are relatively straightforward to understand – they are simply numbers, or codes, that are used to identify you, or your business, for tax purposes. In the UK, every individual needs a National Insurance Number, and if you have a business or need to complete Self Assessment, then you’ll need a Unique Tax Reference number (UTR) as well.

Once we start looking outside the UK, Tax Identification Numbers get much more complex, and given the significance of the fines and other punishments that may be issued, it is really important that you get it right – the success of your business depends on it. Always, always check that you have obtained the right TIN(s), and take advice if you need to. The price of taking professional advice is well worth it, especially when some of the fines for getting it wrong can spell the end of your business if you’re not careful.


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