Hi Adekunle,
Thanks for reaching out.
If you enter or leave the European Union (EU) at an Irish airport or port carrying cash of €10,000 or more, you must make a declaration to customs. Customs may check these declarations and the cash to ensure that the amount declared is correct. You may request a stamped copy of the completed declaration from customs. You can read more
here.
Let me know if you have any other questions, and I would be glad to help.
Cathaoir