A tax reference number (TRN) is the number Revenue uses to identify you for tax. Revenue issues it when you register for tax as a sole trader, partnership, trust or company, and you quote it on every return, payment and letter. For a sole trader, the TRN is simply your PPS number once you are registered with Revenue.
This guide explains who gets a TRN, what it looks like, where to find yours and how it differs from a PPSN, a VAT number and a CRO number. Rules are as published by Revenue and checked on 20 October 2026.
What a tax reference number is
Revenue describes the TRN as the number it issues "when you register for tax as a sole trader, trust, partnership or company". You must use it when trading and when filing your tax returns.
You will see it called different names. Revenue's own pages use Tax Reference Number, while forms, banks and clients often say tax registration number, tax number or tax ID. In Ireland these all mean the same thing: the number on your Revenue record.
Who gets a TRN and when
A TRN only exists once Revenue has registered you for tax. According to Revenue, the registration route depends on who you are:
| Who is registering | Form used |
|---|---|
| Irish resident individual, partnership, trust or unincorporated body | TR1 |
| Irish resident company | TR2 |
| Non-resident individual, partnership, trust or body | TR1 (FT) |
| Non-resident company | TR2 (FT) |
A tax agent can instead register a business online through ROS. Either way, the TRN is what Revenue gives you at the end of the process.
TRN when you work for yourself
If you trade as a sole trader, you do not get a separate number. Revenue states that your TRN will be the same as your Personal Public Service Number (PPSN).
There is one condition: your PPSN does not become your TRN until Revenue has registered you as a sole trader. Having a PPSN from employment or social welfare is not enough on its own. You still need to register for Income Tax, and VAT if it applies, before you can trade and file under that number.
You need a PPSN before you can register at all, so anyone moving to Ireland to work for themselves should apply for one first.
TRN for companies, partnerships and trusts
A company, partnership or trust gets its own TRN, separate from the PPSNs of the people behind it.
A company can only register for tax once it has been incorporated. Revenue's guidance for new companies says you must have a number from the Companies Registration Office (CRO) first. The same registration can cover Corporation Tax, PAYE as an employer, VAT and Relevant Contracts Tax, all under the one TRN.
After registration, the company files all returns and payments online through ROS, quoting that TRN.
What a TRN looks like
For individuals, the TRN is the PPSN, which the Department of Social Protection issues as seven digits followed by one or two letters, for example 1234567D or 1234567DA.
Revenue does not publish one fixed format for company TRNs. Its Stamp Duty manual notes only that the last character of a company's number may be the letter H. The safest approach is to copy the number exactly as it appears on Revenue correspondence or in ROS.
Two numbers are easily confused with a TRN:
- a number ending in W as the ninth character is an old PPSN format for married women, which the Department of Social Protection has replaced
- a number ending in H for an individual can be a Local Property Tax number, which is not a PPSN and cannot be used as a TRN
Where to find your TRN
If you are already registered, the number is on almost everything Revenue sends you.
For a company, partnership or trust, look in:
- ROS, where the number appears on your record and on every return filed there
- Revenue's registration confirmation, issued when the registration was completed
- Past returns, such as a CT1, Form 11 or VAT3
- Statements and letters in your ROS inbox
- Your tax clearance details, since Revenue's verification letter shows the applicant's TRN next to the Tax Clearance Access Number
- Your accountant or tax agent, who will hold it on file if they registered you
For a sole trader, your TRN is your PPSN. You will find it on your Public Services Card, on letters from the Department of Social Protection and Revenue, on payslips from any past employment, and in Revenue's myAccount service.
If the company was registered by a formation agent or a previous accountant and you cannot find any paperwork, ask them for a copy of the registration confirmation rather than registering again.
How the TRN differs from other Irish numbers
These four numbers come from different bodies and do different jobs.
| Number | Issued by | Who has one | Used for |
|---|---|---|---|
| TRN | Revenue | Every person or entity registered for tax | All Irish tax returns, payments and Revenue contact |
| PPSN | Department of Social Protection | Individuals | Public services, employment, and tax as the sole trader TRN |
| VAT number | Revenue | Businesses registered for VAT | VAT invoices, VAT returns and EU trade |
| CRO number | Companies Registration Office | Companies and registered business names | Company filings such as the annual return |
The CRO number is not a tax number. It identifies the company on the public companies register and is needed before tax registration can start. Our guide to the company registration number in Ireland explains where that number appears and how to look it up.
How the TRN is used for VAT
Every VAT-registered business has a TRN, but not every business with a TRN is registered for VAT.
Once a business is registered for VAT, its Irish VAT number is usually built on its TRN, quoted with the country code IE in front for EU trade. Revenue's EORI guidance, for example, asks traders to enter their existing VAT number prefixed by IE. That IE format is what EU customers and suppliers check in the VIES system.
So a business that has not registered for VAT can quote its TRN on tax returns but cannot put a VAT number on its invoices or charge VAT.
If you do not have a TRN yet
You get a TRN by registering with Revenue, and the route depends on your structure:
- Sole trader. Get a PPSN first, then register for Income Tax as self-employed through myAccount or ROS. Your PPSN becomes your TRN.
- Company. Incorporate with the CRO first, then register the company for tax with Form TR2, or Form TR2 (FT) if it is not resident, or through a tax agent on ROS.
- Partnership or trust. Register with Form TR1, or Form TR1 (FT) if it is not resident.
If you would rather hand this over, we handle tax registration with Revenue for sole traders and companies, including Corporation Tax registration for newly formed companies.
FAQ
What is a TRN number in Ireland?
It is the tax reference number Revenue gives you when you register for tax. You quote it on every return, payment and letter to Revenue.
Is my PPSN my tax reference?
Yes, if you are an individual. For a sole trader, the PPSN becomes the TRN once Revenue has registered you for tax.
Does each company get its own TRN?
Yes. A company has its own TRN, separate from the PPSNs of its directors and shareholders.
Is a TRN the same as a tax registration number?
Yes. Revenue calls it a Tax Reference Number, but tax registration number, tax number and tax ID are used for the same thing in Ireland.
Do you get a separate TRN for each tax?
Normally not. Revenue registers a business for its taxes, such as Income Tax or Corporation Tax, PAYE and VAT, under its TRN. A VAT-registered business usually quotes that same TRN with the IE prefix as its VAT number, while a business without VAT registration has a TRN and no VAT number.
Is the TRN issued by the Companies Registration Office?
No. The Companies Registration Office issues the company's CRO number at incorporation. The TRN comes from Revenue when the company registers for tax.
