Can I apply for a WHA in Ireland?

No. Working Holiday Authorizations for US citizens are only processed in the US. Applications must be lodged at a Consulate or Embassy in the US, depending on the residence of the applicant, and issued to the applicant before they depart for Ireland. Applicants must have the Authorization in hand when entering Ireland for immigration purposes.

Once in Ireland, applicants must make an application with the Garda National Immigration Bureau (GNIB) for temporary residence. Applicants must have the Authorization to apply for residence with the GNIB.