If one has a Irish visa, can one travel to Northern Ireland on an Irish visa?
What if one wants to visit both the Republic Of Ireland and Northern Island?
This is generally not possible, as visas for the CTA are not valid for both countries :
You cannot travel to Northern Ireland using an Irish visa, except if travelling under the British Irish Visa Scheme (explained above). You need a visa issued by the United Kingdom.
If you travel from the Republic of Ireland to Northern Ireland and then wish to return to the Republic, you must have a Multiple Entry visa (explained below).
If you are a Chinese or Indian citizen living in your respective country then the situation may be different, but for most nationalities you need a visa for both countries.
No, with the default Irish Visit (Tourist) Visa you cannot enter the United Kingdom (including Northern Ireland).
Only with a visa issued against the British Irish Visa Scheme or a combination of Irish and UK Visitor visa is traveling between the Irish Republic and the United Kingdom possible.
Note:
The Common Travel Area rules apply mainly to Irish and British Citizens
During your stay in Ireland
Travel to Northern Ireland & United Kingdom You cannot travel to Northern Ireland using an Irish visa, except if travelling under the British Irish Visa Scheme (explained above). You need a visa issued by the United Kingdom.If you travel from the Republic of Ireland to Northern Ireland and then wish to return to the Republic, you must have a Multiple Entry visa (explained below).
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