Updated on 6 April 2026

Cross-border workers

Cross-border workers (also known as frontier workers) are individuals who regularly travel from one country to another to work. For example, this might be someone who lives in the Republic of Ireland but travels to work in Northern Ireland (which is part of the UK). We explain what it means to be a cross-border worker with regards to your tax and social security (National Insurance) obligations in the UK.

UK border at a London airport
EQRoy / Shutterstock.com

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Tax

First, if you are a cross-border worker, you will need to consider the rules for residence in each country you either live or work in. In the UK, this will be under the statutory residence test. 

You may find that you are ‘dual resident’, that is, resident for tax purposes in more than one country at the same time. 

You may have to pay tax in both the UK and the other country. As such, you will probably have to look at the double taxation agreement between the two countries, if there is one (there is between the UK and Republic of Ireland).

Republic of Ireland residents working in Northern Ireland, for example, have income tax deducted automatically from their salary under PAYE and paid directly to HMRC. They are also likely to be required to declare this income to the tax authorities in the Republic of Ireland.

While a credit will be given for UK taxes, cross-border workers resident in the Republic of Ireland may have a balance of Irish tax to pay to the Irish tax authorities if they pay less tax in the UK than they would have paid in Ireland if they had earned the Euro equivalent of this income there. However, cross-border workers resident in the Republic of Ireland can make use of Transborder Workers' Relief. This is an Irish tax relief which ensures that they do not pay any additional tax to the Irish authorities, unless they have income earned from other Irish sources, such as rental or investment income, or they are jointly assessed for Irish tax with a spouse.

There is no equivalent UK tax relief for cross-border workers resident in Northern Ireland, who work in the Republic of Ireland, so their annual self assessment tax return to HMRC may result in a 'top-up' UK tax liability.

Please note that the Low Incomes Tax Reform Group is a UK-based organisation and we do not provide guidance on Irish tax matters. If you require support on your Irish tax position, please refer to Irish Tax and Customs.

Example – cross-border worker

David has his main family home in the Republic of Ireland, but during the week he lives in a rented flat in Northern Ireland, where he works for a large company. He carries out all his employment duties in Northern Ireland. He also has savings income from a bank account in the Republic of Ireland.

David has income from sources in the Republic of Ireland and Northern Ireland. As he lives in Northern Ireland during the week for work, but lives in the Republic of Ireland the rest of the time he will have to consider where he is resident for tax purposes – he could be resident in either country or dual resident, that is, tax resident in both the UK and Ireland. He will also need to look at the double taxation agreement between the countries, as this will tell him where he should pay tax on the different sources of income.

He will probably have to complete a tax return for each country, that is a UK self assessment tax return and an Irish tax return.

When he is looking at these issues, he will also have to be aware of the tax years and deadlines of each country. The UK tax year runs from 6 April to 5 April, and tax returns must be submitted by the following 31 January (if submitted online). In the Republic of Ireland, however, the tax year is the same as the calendar year (1 January to 31 December), and the deadline for submitting a tax return is the following 31 October.

Social security

The rules regarding the social security position when individuals are working both in the UK and another country can be complicated.

There is information on the social security rules in our pages on National Insurance in cross-border situations.

More information

If you are crossing the UK/Irish border regularly, you may find the Border People useful – they provide information on cross-border taxation, social security and job-seeking, health, education and banking and more.

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