Revenue can investigate as far back as 20 years, depending on the context.
Generally, if you are under investigation by the Irish Revenue, they can go back to the previous six years, plus four more if the omission appears to be intentional.
If you have been deliberately evading tax, the investigation can span up to 20 years.
You should note that while a normal assessment can be challenged or queried as far as 20 years back, Revenue will normally look for a reasonable period before and after a year, to pick up any trends in the taxpayer's affairs. This includes any errors or inaccuracies in accounting, and to capture any new transactions or transactions in the intervening years, which might alter their findings.
Revenue can also request access to financial records from companies, banks, and third parties, such as solicitors and auditors.
If you find that you are under investigation by Revenue, you should seek immediate professional advice and represent yourself or provide Power of Attorney to a reputable tax adviser who can represent you on your behalf.
For further information and advice, you can reach out to Revenue's Tax and Duty Form Helpline:
• Tel: +353 (1) 738 3670
• Locall: 1890 20 33 03
• Email: form-help@revenue.ie
• Revenue website: https://www.revenue.ie/en/tax/it/forms/form-help.aspx