Leaving the UK from Dublin (Brit. Citizenship)

[0000000000me]

Hello, I'm an EEA German citizen and citizen of Argentina, I have both passports I also have the UK permanent residency documents and since Jan 2016. I would like to apply for the British Citizenship however back in July 2016, I left the UK to Austria, this is temporary and I should return to my life in the UK in 2019. I'm a freelancer and I pay all my taxes in the UK. I have my bank in the UK, my investment UK account etc. I do everything I did when I was in the UK but from a different country at the moment.

Backstory:
I returned to the UK in December 2016, and I stayed in the UK until the end of May 2017. I requested my SAR in January and it showed that I had left the UK in July 2016 and returned in December 2016. So I was worried I might have lost my application fee If I had submitted my request to become a UK citizen at that time because I was away for over 90 day within the last 12 months and it showed on the SAR paper. So in the end of May, I left the UK via Dublin, flying from London to Belfast (no IDs were checked during this journey), then I drove to Dublin and left to Austria on my Argentinian passport. I did this so I could avoid being tracked by the UK border and be able to apply to become a citizen.

I'm planning to return to apply for the citizenship in May next year, maybe earlier.

I would like to know if Dublin shares landing and departure cards with the UK? So when I request a new SAR, will the UK know I left from Dublin to Austria?

Kind regards,
Ed

[secret.simon]

Ireland and Britain share passenger data in response to Europe attacks

The Common Travel Area also involves some co-operation on matters relating to immigration issues. A third country national, for example, may be refused permission to enter Ireland if it is their intention to travel onwards to the UK and they would not qualify for admission to the UK under the Aliens (Amendment) Order 1975. Irish immigration officers have the power to carry out checks on people arriving in the State from the UK and to refuse them entry to the State on the same grounds as apply to people arriving from outside the Common Travel Area. These checks are carried out selectively.

In December 2011, the Irish and UK governments agreed measures to secure the external Common Travel Area border. This includes exchanging biographic and biometric visa data and co-operating on establishing information about failed asylum seekers. There is a joint UK-Ireland Common Travel Area Forum which implements these measures.