Irish CRO Number: Format, Where to Find It, How to Check

An Irish company has at least four different numbers attached to it.

Only one of them is the CRO number, and it is the one most forms actually want.

The short answer

Unlike the UK, Ireland uses no letter prefixes. If a number you have been given for an Irish company starts with letters, it is not the CRO number.

What the number looks like

Irish company numbers are issued sequentially, so the length tells you roughly how old the company is.

• Companies registered long ago have short numbers, sometimes three or four digits
• Recently registered companies are at six digits
• There is no zero padding convention the way there is in the UK

This is the single most useful practical difference from the UK system: a five-digit Irish number is genuinely five digits. You do not need to pad it.

CRO number

123456Up to six digits, never a letter prefix

Identity of the company on the register.

• Issued by the CRO at incorporation
• Public, free to look up on CORE
• Never changes

The Revenue numbers

Issued separately, for tax, not identity.

• VAT number: only once registered for VAT
• Tax reference number: for corporation tax
• Employer registered number: only once you pay staff

A number with letters in it is a Revenue number, not the CRO number.

Where to find it

In order of reliability:

1. The certificate of incorporation. Printed on the face of it
2. Any CRO filing receipt or acknowledgement
3. The company's letterhead and website, where Irish law requires it to appear
4. CORE, the public register, free to search

The legal display obligation. An Irish company must show its registered name, company number, place of registration, registered office address and the names of its directors on its business letters and website. The directors' names are a requirement that surprises people used to UK rules.

The four numbers, and which one a form wants

This is where the real confusion lives.

How to tell which is being asked for:

• "Company registration number" or "CRO number" → the CRO number
• "Tax reference" or "tax number" → the TRN, which is not public
• Anything with IE at the front → the VAT number
• A bank or an accountant asking for "the company number" → almost always the CRO number

If you are filling in a form for a counterparty, a bank or a public body and it asks for a single company identifier, it wants the CRO number. It is the only one of the four that is fully public and permanent.

How to check one

Verification is free on CORE, the CRO's public portal.

What free access gives you:

• Company name and CRO number
• Registered office address
• Company status, including dissolved
• Incorporation date
• Directors and secretary
• The list of documents filed

What costs money: the documents themselves, and certified copies.

Three checks worth doing when verifying a counterparty:

1. Status. A company can be listed and still be in liquidation or strike-off proceedings
2. The name matches exactly. Irish companies often trade under a business name that is not the registered name
3. The last annual return date. A company years behind on filings is a signal in itself

For the mechanics of searching the register, including the free Open Data Portal route, that is covered separately in our guide to searching the Irish register.

What does not change the number

The CRO number is permanent, and stays attached to the entity through:

• A change of company name, with the register keeping the previous names
• A change of registered office, including moving counties
• A change of directors or shareholders
• Conversion between company types under the Companies Act 2014
• Restoration after strike-off

It ends with the company. Dissolved company numbers are retired and not reissued. If a supplier's CRO number has changed, you are dealing with a different legal entity.

When the number does not resolve

Four common causes:

1. You have the tax number, not the CRO number. The most frequent error
2. The company is dissolved and your search filter excludes dissolved entities
3. A digit has been transposed, which sequential numbering makes easy
4. It is a business name, not a company. Registered business names have their own numbers and are not companies at all

That last one catches people. A registered business name in Ireland is a trading name filing, not a legal entity. It has no limited liability, no directors and no accounts.

If you are setting up an Irish company and want to know what it must display and file once the number is issued, that sits with the other obligations worth understanding before you incorporate.

The summary